It's All About Relationship Building in "The Fortification Implementation”

When Sheldon and Amy build a blanket fort, they come to major crossroads in their relationship. Also, Wolowitz meets the half-brother he never knew he had, and when Penny is invited to appear on Wil Wheaton's podcast, she and Leonard have a huge, on-air argument, on THE BIG BANG THEORY, Thursday, April 9 (8:00-8:31 PM, ET/PT), on the CBS Television Network. Pictured left to right: Jim Parsons, Johnny Galecki, Simon Helberg and Kunal Nayyar Photo: Sonja Flemming/CBS ©2015 CBS Broadcasting, Inc. All Rights Reserved

Wolowitz meets the half-brother he never knew he had, on THE BIG BANG THEORY, Thursday, April 9 (8:00-8:31 PM, ET/PT), on the CBS Television Network. Pictured left to right: Simon Helberg, Melissa Rauch and Kunal Nayyar Photo: Sonja Flemming/CBS ©2015 CBS Broadcasting, Inc. All Rights Reserved

When Penny (Kaley Cuoco-Sweeting, left) is invited to appear on Wil Wheaton's (pictured right) podcast, she and Leonard have a huge, on-air argument, on THE BIG BANG THEORY, Thursday, April 9 (8:00-8:31 PM, ET/PT), on the CBS Television Network. Photo: Sonja Flemming/CBS ©2015 CBS Broadcasting, Inc. All Rights Reserved

When Sheldon (Jim Parsons, left) and Amy (Mayim Bialik, right) build a blanket fort, they come to major crossroads in their relationship, on THE BIG BANG THEORY, Thursday, April 9 (8:00-8:31 PM, ET/PT), on the CBS Television Network. Photo: Sonja Flemming/CBS ©2015 CBS Broadcasting, Inc. All Rights Reserved

When Penny (Kaley Cuoco-Sweeting, center) is invited to appear on Wil Wheaton's (pictured right) podcast, she and Leonard (Johnny Galecki, left) have a huge, on-air argument, on THE BIG BANG THEORY, Thursday, April 9 (8:00-8:31 PM, ET/PT), on the CBS Television Network. Photo: Sonja Flemming/CBS ©2015 CBS Broadcasting, Inc. All Rights Reserved

Wolowitz meets the half-brother he never knew he had, on THE BIG BANG THEORY, Thursday, April 9 (8:00-8:31 PM, ET/PT), on the CBS Television Network. Pictured left to right: Kunal Nayyar, Simon Helberg, Matt Bennett and Melissa Rauch Photo: Sonja Flemming/CBS ©2015 CBS Broadcasting, Inc. All Rights Reserved

Wolowitz meets the half-brother he never knew he had, on THE BIG BANG THEORY, Thursday, April 9 (8:00-8:31 PM, ET/PT), on the CBS Television Network. Pictured left to right: Kunal Nayyar, Simon Helberg, Matt Bennett and Melissa Rauch Photo: Sonja Flemming/CBS ©2015 CBS Broadcasting, Inc. All Rights Reserved

When Sheldon (Jim Parsons, left) and Amy (Mayim Bialik, right) build a blanket fort, they come to major crossroads in their relationship, on THE BIG BANG THEORY, Thursday, April 9 (8:00-8:31 PM, ET/PT), on the CBS Television Network. Photo: Sonja Flemming/CBS ©2015 CBS Broadcasting, Inc. All Rights Reserved

Wolowitz meets the half-brother he never knew he had, on THE BIG BANG THEORY, Thursday, April 9 (8:00-8:31 PM, ET/PT), on the CBS Television Network. Pictured left to right: Kunal Nayyar, Simon Helberg, Matt Bennett and Melissa Rauch Photo: Sonja Flemming/CBS ©2015 CBS Broadcasting, Inc. All Rights Reserved

Wolowitz meets the half-brother he never knew he had, on THE BIG BANG THEORY, Thursday, April 9 (8:00-8:31 PM, ET/PT), on the CBS Television Network. Pictured left to right: Simon Helberg and Matt Bennett Photo: Sonja Flemming/CBS ©2015 CBS Broadcasting, Inc. All Rights Reserved

In this episode, Penny gets an offer to audition for a movie from Director Kevin Smith (pictured above to the right of Leonard). This behind-the-scenes snapshot shows Kevin enjoying his time on set, who is featured in the episode through a voice-over.