Season 1

The Driver's Seat

Jamie might be a cowardly, useless jerk, but there is something sad about him admitting that Coop is his Only Friend. And that he has to tag along because he doesn't want to be alone even though he contributes nothing to the team.

Season 2

Terminate Her

The Glorrft attempt to kill Kiva by killing her ancestor. At the end of the episode, Kiva admits to her ancestor that she is lonely in the Bad Future as she has no family that cares for her. She asks her ancestor if they want to get to know each other. Unfortunately, the ancestor was like Kiva was when the series started. She wants nothing to do with her or Coop's chaos, leaving Kiva without a family again. The look of sadness on her face sells it. The only Heartwarming assurance is when she thanks Kiva and in retrospect, by her moving away from Jersey and somewhere safer, Kiva's existence is ensured.

Rearview Mirror Mirror, Part 2

Megas has already been damaged several times in the series before, but Coop's evil future self managed to do the impossible and truly finish the giant robot off. Future Jamie tells present Coop to eject, but Coop refuses due to the loyalty he has towards his robot and nearly gets himself killed if it wasn't for Gorath.
Jamie: Coop, you're red-lining! Eject!
Coop: No!! I ain't leavin' Megas!
Future Jamie just sounds broken when he recounts Coop's descent into madness after defeating the Glorrft and Kiva losing her humanity as well especially since they used to date.
- When you consider it, Future Jamie's situation after Evil Coop and Evil Kiva are banished to another dimension is very heartbreaking. His only two friends in the world are now gone and he will very likely never see them again. And even if he did, they obviously will want him dead. He's now living the life of loneliness his past self tried to avoid.
During future Coop's rampage he actually killed the S-Force, unlike the other opponents shown in the montage who were enemies. The S-Force were good friends of Coop, truly showing the part where he only cares about fighting and nothing else.