Transformers Animated/Heartwarming

• In the episode "Return of the Headmaster" when Bumblebee and Bulkhead finally ask Sari if she's okay after she's lost her father and doesn't know if he's alive, had her family's company been taken away from her, been kicked out of the only home she's ever known, had Tutor Bot and Sparkplug confiscated as company property, and to top it off been informed that there is no legal record of her existence. Sari explains as much angrily, then bursts into tears. Having seen this before, Bulkhead comments that her eyes are leaking. Bumblebee picks her up and says:

Bumblebee: You let'em leak as much as you need to. We're here, and you're safe. So whatever it is, you can always talk to us. We'll listen.

• The reconciliation between Sari and her father in spirit, at the very least at the beginning of Season Three after he stands up to the Headmaster, who was currently piloting Starscream was just adorable fluff.
• Omega Supreme's introduction to Ratchet, his new (but unwilling) mentor.

Omega Supreme: I am Omega Supreme. I am yours to command. I am your pupil. Your dependent. Your obedient servant.
Ratchet: I am Ratchet. I am... your friend.

• • At the end of the series, the reaction Omega Supreme gets when he reveals himself to the Autobots. He transforms into robot mode and the crowd stops cheering... only to start cheering even louder. Keep in mind that the Supremes were one of the contributing factors to the Autobots winning the Great War, and afterwards everyone had been (falsely) told that Omega had been melted down into scrap.
• Don't you dare forget this exchange between Optimus Prime and Sari. (at the very end of the series no less, a definite show of how their relationship has changed)

Sari: I know, I know. It's too dangerous. It's always too dangerous.
Optimus Prime: I was going to say, it's more important for you to protect your father and your fellow organics.
Sari: (sheepishly) Oh. Sorry.

• The mind-controlled human Prowl playing peek-a-boo with a baby in "Human Error, Part 1." It's brief, but very cute.