At the cafeteria, Howard and Raj are arguing whether Internet animation files are pronounced "jif" or "gif". No conclusion is reached as Sheldon shows up quite irritated. He wasn't invited to a weekend physics symposium at one of Richard Feynman’s former home for a group of elite scientists. Howard tells him that it was probably because he is a pain in the ass and Sheldon says that he's just saying that to make him feel better.
Raj brings Howard and Bernadette a house warming gift, nine boxes of Girl Scout cookies. They now have clear title to his house since his lawyers tracked down his father and he signed it over to him. Howard didn't meet him and doesn't want to know where he is. Raj wonders if he is in prison, or a spy or playing Ringo in a Beatles' cover band.
Amy and Sheldon are having a Date Night dinner and Sheldon is still very depressed. He hopes that an asteroid hits the house the symposium is being held in. Since that is not going to happen, Amy is in for a cranky night. The Relationship Agreement dictates that they cannot pout or be moody on Date Night. To counter this codicil, Sheldon hides behind a happy face mask.
While Raj and Bernadette discuss redecorating ideas, the doorbell rings. A young man is there and tells Howard how a lawyer contacted his father, Sam Wolowitz, about the title on that house. Since Sam was Howard's father, that makes the young man, Howard's half-brother. Howard calls and tells Bernadette that weird things were happening.
Penny is answering a question that she first knew it was a bad movie when she read the title: Serial Ape-ist 2: Monkey See, Monkey Kill. Wil invites Leonard to join the podcast. One caller says that she loves the movie and saw it ten times. Penny apologizes for the first time, but the other nine are on the caller. The movie has become a cult classic and Wil saw someone at a convention dressed up as Penny's half-ape character. Next actor/director Kevin Smith calls in and is a big fan of the movie and he loved Penny's performance. He wants Penny to audition for his new movie "Clerks 3". Leonard reminds her that she already has a job; however, Penny didn't ask him.
Sheldon is talking to Amy about being left out of things in his life including the forts built by his brother and sister when he was growing up. Amy can't get him invited to the symposium, but she suggests that together they could build their own fort. Sheldon runs off to get the blankets while Amy is supposed to Google how to have child-like fun.
Howard runs off to get more coffee leaving Josh with Bernadette and Raj. He is an oceanography student in San Diego; while Bernadette loves "Finding Nemo". Raj challenges him as to who he really is though who would still claim to be a Wolowitz? Does he want money, a kidney or for Howard to replace his father as Ringo in a Beatles' cover band? Bernadette sends him after Howard. Howard is upset that Josh shows up and that his father has another family. Howard wants to tell Josh to leave until Josh exclaims how amazing that his brother is an astronaut. Howard starts to explain about the greatest adventure of his life.
Wil is having fun hosting Penny and Leonard's fight about her career, though Penny says that it's just a discussion. Penny reminds him that they could have a wonderful life if she becomes rich and famous. Leonard reminds her that it is a Kevin Smith movie. Kevin then hangs up on them. Leonard is just trying to protect her after all her other acting disappointments. Penny just wants him to be happy for her. He was happy for her when she got her current job that pays a decent wage. Decent? She makes twice what Leonard makes. Leonard went to school half his life and still has college loans, which Penny offers to help him pay off.
Finishing up their fort, Amy comes in to check out the Christmas lights Sheldon hung inside. They find their fort amazing and then rough it by sitting on the floor.
Howard is entertaining Josh with magic until he figures he has to go. Howard hopes to see him again. Josh has always dreamed to have someone to play catch and Bernadette tells him that he'll have to keep dreaming. Howard mentions using the robot to do it, and Josh thinks he means sex. Howard did build a robot arm. Josh thinks that that is all you need. Howard hugs him telling Josh that he is definitely his brother.
Penny has been putting together a diversified portfolio of stocks and bonds with her broker. Leonard says he doesn't because he doesn't have any money. Leonard wonders who the mature one now in this relationship is. Penny asks him if he would feel better if she did something stupid like sneaking out from work and trying out for a Kevin Smith movie? Leonard agrees and Wil Wheaton comments that Penny just played him like a violin.
As date night draws to a close, Sheldon and Amy are finishing their first annual greatest fort ever contest. Their fort (Fort Cozy McBlanket) beats Fort Knox. After Amy's alarm goes off, Sheldon isn't ready to stop and suggests that they extend the Date Night parameters. Amy suggests their first sleepover. Sheldon is fine as long as it is G-rated, though Amy is pushing for PG. Does she need pajamas or a toothbrush? Amy had previously hid a set under the couch cushion in case she ever spent the night. And there might be another set in Sheldon's bedroom.
Leonard returns home and finds the fort built using his sheets. Sheldon wants Leonard to ask to come in just so he can say no. Leonard agrees and asks to come in. Unfortunately, Sheldon thinks it's such a great fort that he can't say no, though he won't let Leonard sit in his spot.
- Guest starring:
- Teleplay: Steven Molaro, Steve Holland & Maria Ferrari
- Story: Jim Reynolds, Saladin K. Patterson & Tara Hernandez
- Title Reference: The title refers to the fort that Sheldon and Amy built together.
- Taping date: March 10, 2015
- This episode was watched by 14.78 million people with a rating of 3.5 (adults 18-49).
- Total viewers including DVR users 19.66 million.
- The Big Bang Theory was ranked #2 for the week ending 12 April 2015.
- This episode aired in Canada on April 9, 2015 with 3.89 million viewers with a weekly ranking of #1.
- In Australia, it aired on April 20, 2015 with 0.91 million viewers.
- Broadcasted in Great Britain on the E4 channel on Thursday, May 21, 2015.
- Episode transcript 
- Jesse Schedeen for IGN-..."The Fortification Implementation" came along at a good time. Though it focused on three separate, smaller storylines, this episode wound up offering some tangible progress for several characters and running threads...The most significant of these three storylines involved Howard meeting his long-lost half-brother...(Josh, though he}...wasn't given much to do but sit on the couch and make brief, awkward conversation...Elsewhere, Wil Wheaton guest-starred for the umpteenth time as he invited Penny onto his podcast to discuss all things Serial Apist 2. We quickly learned that Penny has actually developed a cult following...(and)...it's good to see Leonard wrestle with being the less successful one in their relationship for a change...The blanket fort was a charming plot twist, and it wound up resulting in the very first boy/girl sleepover of their relationship. A G-rated sleepover, perhaps, but that's still a pretty huge victory for her.
- Sheldon and Amy spend their first night together in his apartment though the night is rated G.
- "Clerks 3" is scheduled for release in the summer of 2016 and stars Rosario Dawson, Kevin Smith, and Jason Mewes.
- Penny has a chance to restart her acting career with an offer to be in the movie "Clerks 3".
- Penny earns twice the money that Leonard does changing the financial balance of their relationship. She turns the tables on him and gets him to agree to letting her try out for the part.
- Earlier in the season Penny was worrying about her big credit card debt and now is offering to help Leonard pay off his student loans.
- This episode has references to the episodes "The Robotic Manipulation" (S4E1), "The First Pitch Insufficiency" (S8E3) and "The Gorilla Dissolution" (S7E23).
- Sheldon brings up Schrödinger again as in Schrödinger's Cat. The scientists at the symposium may be talking about it and at the same time may not be talking about it referring to his experiment.
- Since Penny had been partially supported by Leonard for years, she better have a great need to help him out now.
- Howard's father left him when he was a child and now Howard is thrust into the father figure role with his new younger half-brother Josh.
- The initial first round candidates in the first annual best fort ever contest were Fort Cozy McBlanket, Fort Bragg, Fort Benning, Fort Sumter, Fort Ticonderoga, Fort Irwin, Fort Wayne and Fort Knox.
- Howard's father's first name is revealed to be Sam.
- Bernadette is only seen at the Wolowitz house in this episode and she shares no scenes with Amy, Leonard, Penny and Sheldon in this episode. As of this episode, Bernadette is the only gang member not to meet up with Wil Wheaton since a few episodes in the previous season (1: S7E10, 2: S7E19 and 3: S7E23), six other previous season episodes (1: S3E5, 2: S4E8, 3: S5E5, 4: S5E22 and 5: S6E7) and her absent appearance in Season 3's "The Wheaton Recurrence" (S3E19).
- Josh, unfortunately, doesn't meet Leonard, Sheldon, Penny and Amy in the episode, but strongly surely will soon.
- Raj's collection of Girl Scout cookies are using the old box designs and not the ones used in 2015.
- Raj: So how’s it going with the title to the house?
- Howard: Great. It’s all done. The lawyer tracked down my father and got him to sign it over. I didn’t have to meet him, I didn’t have to talk to him, I don’t even know where he is.
- Raj: Wow. So you’re not even curious at all?
- Howard: Nope.
- Raj: What if he’s in prison? What if he’s a spy? What if he’s in a Beatle’s cover band? I’m just saying, if he’s got your nose and haircut, He’d make a killer Ringo.
- Penny: What? A few thousand people listening to you talk about Nerd stuff?
- Amy: According to the codicil of the Relationship Agreement which you insisted upon, we’re not allowed to pout or be moody on date night.
- Sheldon: You know I just put that in because of uterus stuff.
- Bernadette: When he’s at Comic-Con, I’m bringing in a wrecking ball.
- Howard: Wait, who’s your father?
- Josh: Sam Wolowitz.
- Howard: (chuckles) S-Sam Wolowitz is my father.
- Josh: I know.
- Howard: Well, wait, so if we have the same father... I mean... are you saying you’re my half-brother?
- Josh: I think so.
- Howard: Bernadette, weird things are happening out here!
- Wil: Let’s take a call. Hello caller, you are on with Penny and Wil from Serial Ape-ist 2.
- Caller: I don’t have a question. I just to say I’m a big fan of the movie. I’ve seen it like ten times.
- Penny: Okay, well, I’ll apologize for the first time, but the other nine are on you.
- Kevin Smith: So Penny. I saw your movie.
- Penny: Oh, wow. I wish it was better.
- Wil: Oh, don’t worry about it. Have you seen some of Kevin’s films?
- Kevin Smith: You’re crusin’ for a beatin’, Wheaton. Anyway, man I dug ape movies, Penny. And I thought, like, you were really great in in.
- Penny: Aw.
- Wil: You know I’m in the movie, too.
- Kevin Smith: Yeah, whatever. Penny! Penny, how come you’re not in more stuff, man? I’d cast you in a minute.
- Penny: Seriously?
- Kevin Smith: Oh, yeah, man! I’m actually in pre-production on a movie right now. Way different than anything I’ve done before. It’s called Clerks 3. You should come over and read for a part.
- Penny: Oh, my. I would love that.
- Leonard: You have a new job.
- Penny: Well, maybe I can do both.
- Leonard: I don’t think you can do both.
- Penny: I don’t think I asked you.
- Leonard: I’m just trying to protect you. How many times have I seen you get your heart broken trying to make it as an actress?
- Penny: Okay, instead of protecting me why don’t you try getting excited when something good happens?
- Leonard: I’m always excited for you. I’m excited that you found this new job where you’re making decent money.
- Penny: Decent? I make twice what you make.
- Leonard: Wait, twice?
- Penny: Yeah.
- Leonard: Like “times two” twice?
- Bernadette: So Josh, what do you do?
- Josh: I'm studying oceanography down in San Diego.
- Bernadette: Oh, how nice. (moment of silence) I loved Finding Nemo.
- Raj: (sternly) Enough chit-chit. How do we know you are what you say you are?
- Josh: Why would I lie?
- Raj: Okay, you got me there.
- Josh: I’ve always dreamed about having a brother to play catch with.
- Bernadette: Keep dreaming.
- Penny: Leonard. Why are you making such a big deal about this? So our roles have changed a bit over the last couple of years. That’s the way life is. And I’m sure in time they’ll change again.
- Leonard: Great, you’re not only more successful than me, now you’re more mature.
- Penny: Okay, look, would it make you feel better if I did something dumb like sneak out of work one day to go audition for a Kevin James movie?
- Leonard: That would be great. Thank you!
- Wil: I’m just going to jump in real quick Leonard, a moment ago you were dead set against Penny resuming her acting career, but now you're all for it. Is it fair to say she played you like a violin?
- Leonard: Yes, it is, Wil.
- Amy: Well, as long as we’re suspending the parameters, I could stay really late and we could have our first sleepover.
- Sheldon: That’s a big step.
- Amy: It’s a big fort.
- Sheldon: Very well. I will agree to a family-friendly, G–rated, boy-girl sleepover.
- Amy: PG. Some scenes may be too intense for younger viewers.
- Sheldon: G rated, with a warning for families with babies and toddlers.
- Amy: You got yourself a sleepover.
- Sheldon: Do you need to borrow a toothbrush or pajamas?
- Amy: Would it alarm you to know that I hid those things here two years ago just in case this ever came up?
- Sheldon: It would, but you know how much I admire preparedness. How did you know we’d be in the living room?
- Amy: Who said this is the only one I hid?
-  Taping Report by Senior Member and Rule34