maybe in another life

What if Reg wanted him to live happily, to spare him pain?

Every time I see you in my askbox I know you're gonna coming with something great to say. And hahaha. I agree that line is incredibly telling. Clearly it's evidence that Harry care deeply for Bellatrix and has decided to be the bigger person and move on from the whole murdering Sirius thing...lol jk. Yeah. There is literally only one person in that room that Harry could be referring to here.

And remember, he thinks about those he left behind at the Manor in the context of sensing through his connection with Voldemort that they are being brutally punished.

Draco didn't reveal Harry's identity. Draco let Harry take his wand. Draco didn't report it when he saw that Harry and the others had untied their bonds while locked in the basement cells. Draco has been having doubts about being a Death Eater and doesn't want to be there. If Voldemort realizes any of this he will surely kill Draco - probably not quickly - and even if he doesn't, he might do that anyway.

Harry knows that as a result of his escape Draco is going to be hurt, and quite possibly killed. In this scene, he knows it's happening right now at this very moment and he can't do anything about it or even let himself dwell on it. But part of him wishes that he could, that he could back and save Draco or that he had brought him along. Maybe he doesn't fully acknowledge that, even to himself, but it leaks through in how he thinks about events. JKR didn't mean it that way, but that's she wrote.

I've talk about this before but it's really notable how the first time Harry successfully blocks Voldemort out is in this moment. I read as this being evidence of that fact that he is so motivated to not see Draco being tortured or killed that for the first time EVER he manages to fully close his mind. Also, the Manor sequence is a turning point for Harry. It's when he becomes fully committed to ending the war, and ending it now, to destroying the Horcruxes whatever the cost and focusing solely on that mission on not on the Hallows or on wondering about Dumbledore's true motives. Seeing Draco, and knowing that the price of his escape may well be Draco's life seems to shift something in him.

Also shoutout to the fact that when escaping the Manor the last thing he does is look back at where Draco is despite all the chaos going on:

«IF LOST RETURN TO R.A.B.»

James: Forty five seconds?!?

Regulus: No! I said four TO five seconds.