Heartwarming / Abridged on Titan

• Episode 4, also doubles as a CMOF when Jean decides he can't let Mikasa go off alone, so he rallies the troops.
  Jean: “Damn it…okay guys, listen up! If Mikasa dies, there goes my chance of hitting that! So we’re all gonna help her out!”
  Random Soldier: “That’s not very inspirational!”
  Jean: “Also WE’RE SOLDIERS AND STUFF!”
• In episode 5, when Marco tells Jean how much he appreciates having faith in him, and further adding that no one else really even knows him, and how much he likes having Jean as a friend. It makes Jean feel genuinely guilty for the way he'd acted up till that point.
• Mikasa's freak out and ensuing BSOD over being told that Eren was eaten. Despite how she acts most of the time, it's sweet to see that she cares about him as more than a babysitting charge.
• Not immediately apparent, but remember in the short "Mee-ka-sa" where Mikasa says she stopped caring about Eren constantly mispronouncing her name six years ago? Well, given the time this short takes place in, six years ago, Eren saved Mikasa's life. Of course she wouldn't care.
• Even though the context of the situation means that they're totally screwed because of it, the fact that Eren's uncharacteristic lack of desire to kill Annie when she goes on a rampage as the Female Titan is due to him still viewing her as an old friend of theirs.
• In the Season 1 Finale, after years of Eren feeling bitter at Mikasa for being his mother's favorite and outshining him in every way, Mikasa tell him that he's her favorite. Eren takes the compliment, if a bit bluntly, and it actually comes across as more sweet than most of their canonical interactions.