A part of the drama in the story has been of Nanase being afraid to come out, to her family in particular, and the difficulties that this has caused, including insisting that the relationship be kept secret. When her partner's life is in jeopardy, however, she literally risks her life to save said partner; this is not, however, the Heartwarming Moment itself. Later, while she lies in the hospital, recovering from her brush with death, her partner by her side and in tears, and having just being told that it may be months before she can again use magic, having burnt herself out in defense of the one that she loves, we have the following exchange between her and her partner:
"Small price to pay. You're alive, that's all that matters."
"I... You know what I want to say, but I know you wouldn't want me to say it in public..."
"I love you too, Ellen."
And then in later strip, when Nanase thinks her mother is okay with her lesbian relationship ... but subverted as it turns out she just doesn't take it seriously, thinking they'll eventually grow out of it.
And her next line immediately after that. She is able to put her disagreement aside and remember that her daughter could very well have died that evening.
Nanase's Mother: Shh... We have all the time in the world to argue.
This page shows Nanase's mother genuinely happy that shy, little Tedd has a girlfriend; yet again proving that while Nanase's mother may be Jerkass-ish in certain ways, she still has her moments.
This comic. To see the formerly shy Tedd so firmly defend what was essentially a big string of screw ups is rather smile-inducing.
Especially his choice of words: "If you're the result of my mistakes, then they were the best mistakes I ever made." Awwwww...
Thesestrips at the end of the Sister plot arc are both a heartwarming and awesome moment for Elliot. Why do you think Ellen is so protective of everyone? Keep in mind that just before this, Ellen thought that she was going to die and had told Elliot that she was going to do nothing but cause trouble for him, yet he still sticks up for her.
"This is the fifty-sixth day we've been together." "You know how many days we've been together?" "...Maybe."
This. Just think about it: Tedd could choose ANYONE for his bridge crew. He could have tons of different women in short skirts and Star Trek shirts, but instead he wants them all to look like Grace. Awwww.
Doubles as a Tear Jerker. Near the end of Sister II, as Angel!Nanase has Abe in her grip, she makes her tell him what he promised, but not what he said. She reminds him that he promised to protect innocents, and, despite being born of the Dewitchery Diamond, Ellen was an innocent. The look on Abe's face as he realizes that he can't harm Ellen (especially since he was very reluctant to do so in the first place), and his exclamation of relief just pulls at the heartstrings, especially when he instantly swears not to harm Ellen when told to.
This strip where Susan comforts Justin after he reveals the story of his traumatic outing and his unrequieted crush on Elliot.
Justin ...I'm alone, and I just don't see that changing... Susan: You're not alone, Justin. Justin: Huh? Susan: You have Nanase, Ellen, Tedd, Grace, Sarah, me, and even Elliot. You haven't known all of us for very long, but we're all your friends. Being single is not the same as being alone. It may suck that you can't be romantic with the one you love, but you have people who care about you, and they like you for who you are.
Also, theaftermath of the Big Damn Kiss. It really shows just how good their friendship is for those two. Susan manages to help relieve a little of Justin's worries, and Justin helps Susan on the path to overcoming her own issues.
Elliot's brief summary of what went through his mind when Ellen was created by the Dewitchery Diamond. It was an unbelievably disorienting experience for Ellen, but for Elliot...
Elliot:I've never been this confused before. Ellen: Oh, sure you have. What about after you touched the diamond? Elliot: That was pretty simple, actually. Ellen:Really. The spontaneous creation of a female twin with all of your memories. That was simple. Elliot: "She's family. Help her." Not that complicated.
When Susan discovers that Tom's friendly overtures towards her were actually part of his attempts to manipulate her into asking him out, she calls him out on it, takes him down a peg and completely obliterates his attempt at a Hannibal Lecture. After the altercation, Sarah asks her if she's okay. Susan's reaction: spontaneous hugging.
Near the end of the "Identity" arc, when Diane receives Susan's thank-you message and realizes: "This is from my sister." Her expression in the last panel combined with the realization is what really sells it.