Hana Hime's room

When he doesn’t have a clear mission objective, he is following his motto: “do what your heart tells you” / “act on your emotions”-- which is way, way less whimsical and than it sounds (see this entry in the Dictionary section). It’s an extension of the Unthinking: You encounter a problem, you find a solution. Does this feel right? If yes, proceed. If no, then don’t. Was it the wrong solution? Well, that’s a new problem.

If you’re Heero’s problem, you have a very limited window of opportunity to change his mind about it. If you’re Relena, you get another chance. If you’re Marshal Noventa, you don’t. If you’re a fellow Gundam pilot, you might be able to hold him off long enough for the problem to become a different problem. 

Heero was built from the ground up several times by the people who found him and turned him into what he is: a weapon that you aim and fire. That’s how he thinks of himself, as a machine with a single purpose that you input instructions into, and when he stops working at peak performance, he’ll die and be replaced. 

But the people who were there for his “training” know that there was a human boy underneath that they buried to make their perfect soldier. Sometimes, you can still see him through the cracks.

There are only a few times in canon when we see Heero laugh or smile; I found it a very interesting case study to track when and where he does so. In chronological order, the first time is in a flashback from Endless Waltz; it’s a very memorable scene, because it’s the most innocent and carefree we ever see him, but the thing he was doing directly before flopping onto the grass and laughing wholesomely was planting explosives in a military base. The outcome of this scene is a defining tragedy of his life, which we know was the cause of his needing to be “retrained”.

The other few times he laughs are sometime after this incident, when he first arrives on Earth.

In episode one, we get to see him smile and laugh. The smile is one of simple relief, because he’s completed his objective– but what he actually considers that objective to be is a bit complicated. The simplest answer is that he’s successfully made it from the Colonies to Earth, so he can start his mission as a resistance fighter, but the more relevant answer is that arriving on Earth has the potential to be his FINAL mission as the person who stole the Gundam in order to interrupt Operation Meteor. The smile is either because he’s made it past the first difficult step of his journey, or because this is where his journey can finally end. 

In this same episode, he laughs after making his first kill; hapless OZ pilots who had no idea what they were up against. Later on, he laughs because he completes a mission after repairing his Wing Gundam with the cannibalized parts of Duo’s Gundam, Deathscythe. Another time, he smiles with an aloof assurance that he does not need to participate in the frivolities of civilian life, as if he’s confirming to himself that he is not like the people he is infiltrating. He’s a robot, disguised as one of them. He doesn’t need to worry about understanding them, or sympathizing with them, or trying to form emotional connections that he isn’t capable of making. He smiles when he cuts down what he thinks is an OZ carrier leaving New Edwards Base.

These are all times when Heero feels like he’s gotten away with something; when he’s pulled off something sneaky and gotten away scot free. It’s a cathartic release of excitement that's a touch mischievous; the surviving traces of his adolescence bubbling up and escaping containment.

Heero doesn’t laugh again after his first failed mission at New Edwards. Even when he cracks a joke, even when he's relaxed, his face remains frozen. There's only one more time when he smiles: when he’s sure he’s on his last mission, the one he won’t come back from, and he knows he has someone he wants to protect. 

It is such a simple, kind, naive thing that lets Heero unlock the capacity to feel; he’s never had someone be on his side before. Just… decide that they care about him, for no reason in particular– indeed, after he’d given them ample reason NOT to. It’s not perfect, not a clean process, not all at once. He gets feelings back one at a time, in broken pieces that are sharp and don’t make sense at first. A girl who he thought he would have to kill decided that she would trust him absolutely and have his back no matter what, and that made everything uncertain. 

It’s more complicated to live with danger when there’s something to live for, when someone insists that you’re worth saving. It means you have to think about the future sometimes, and that means dealing with consequences, and disappointment, and worry, and pain. It means having to develop a sense of compassion, without which it would be so easy to just turn off, and listen to the comforting absolutes of a machine that tells you how to win and who to kill. 

Having something, someone, to lose is frightening– but it gives you a fixed point in the sky to follow, so when you’re facing down ultimatums, and sacrifices, and uncertainty, “winning” becomes less important than keeping who you care about safe.

It makes your heart a much better compass to follow.