As its cast has grown, some episodes of The Big Bang Theory haven't balanced the characters' screen time. Last night's episode was well balanced and showed Sheldon had come far in six seasons.
The university decided Sheldon and Barry Kripke (John Ross Bowie) should work together on a proposal for a fusion reactor. Sheldon balked at the idea of working with one of his enemies, but also admitted to the gang that Kripke's research was better. For his part, Kripke saw potential in Sheldon's ideas but assumed he wasn't at the top of his game because his relationship with Amy was further along than it was. Rather than admit inferiority in front of Kripke, Sheldon simply went along with the assumption.
Meanwhile, Raj and Howard ordered custom-made action figures of themselves, but Leonard had the good sense to pass. When the figures weren't as either of them hoped, Raj and Howard decided to improve them with a 3-D printer. Howard's free spending gave Bernadette an angle into the episode.
Finally, Penny asked about the state of Sheldon and Amy's relationship. Sheldon conceded he was "quite fond of Amy" and the relationship could get physical someday, leaving Penny agape with excitement.