#9.01

When he first shows up, he behaves like (the romanticized version of) a medieval knight. Like. Listen to his dialogue when he first appears to rescue Dean from an angel beating the shit out of him.

GADREEL/EZEKIEL: Easy there, brother. This young man has prayed for our assistance. Are we creatures of wrath or compassion? I would argue the latter.

He has a very (charmingly) "old fashioned" take on angelic duty. He believes it's their job to help humans. His ultimate sacrifice reinforces that that isn't something he made up to manipulate Dean—he really truly believes what he's saying and he wants to be a good and righteous angel! His attitude is almost like season 4 Cas (who is so convinced that he's on a holy mission) but actually less cynical—more chivalrous.

He's already been injured by the fall, but when he hears Dean's prayer, he makes his way to him for no other reason than Dean prayed for the help of an angel!

He tries to deescalate the situation:

ANGEL: Forgive me, brother. I don't recognize you. GADREEL/EZEKIEL: Happy to make your re-acquaintance. After you disarm. [The angel pretends to be willing to talk but then attacks Gadreel] GADREEL/EZEKIEL: Come, now. Is that any way to treat a brother injured in the fall?

He indicates that (while we know he was in prison so he couldn't actually take action) he rooted for Cas's side.

GADREEL/EZEKIEL: Believe it or not, some of us still do believe in our mission. And that means we believe in Castiel...and you.

And of course—Cas's little mistake freed him from prison, so that's another reason he's not pissed at Cas like the rest of the angels. That said, I don't think Gadreel is being dishonest about being on Cas's side. I just think when the time comes, he's still too scared that Cas will reject him to risk an encounter (and that fear doesn't turn out to be unfounded to be fair).

He also chooses the alias of an angel Cas ends up vouching for with a smile, calling him a "good soldier". While I think Metatron is right to say in 9.09 that Gadreel chose to take Ezekiel's name because he had a good reputation (something Gadreel sorely lacks) I think his choice also suggests Gadreel and Cas have similar values, because they hold the same angel in high regard—and the angels in general liking some angel doesn't necessarily mean Cas thinks that highly of that angel, considering how much Cas has morally clashed with the rest of his brethren.

I've also talked before about Gadreel's vessel choice being very interesting. Almost all the other angels (the only exception I can think of being Samandriel) choose vessels that work corporate jobs. Their attire (among other things) aligns them with the upper class. Gadreel, on the other hand, asks a bartender to be his vessel. I think it's interesting that the two angels Dean seems to trust most immediately end up being Gadreel and Samandriel... and they ARE both angels who share Cas's stance on humanity more generally. At the same time, they're also not human, and just as we see with Cas sometimes, we see with Gadreel in season 9 that fealty to certain ideals leads angels (with the soldier's mindset) to be ruthless when they believe they are required to be to be righteous. And reputation matters a lot to them (see: season 6 Cas hiding what he's doing from absolutely everyone he knows, keeping Crowley as his dirty little secret).

Gadreel's problem is that his sense of chivalry is dampened by the terror he feels at the idea of being found out and thrown back into a cell for eternity. He wants to repair his reputation, and Metatron convinces him that restoring order in heaven will please God and re-legitimize him. Cas's season 4 mistakes were centered around the belief that he was serving God, which is what Metatron sells Gadreel on, and like Cas in season 4 (and again in season 12), Gadreel is also lured by the concept of paradise.

METATRON: You and I ... We could have paradise again, Gadreel.

Even when Metatron demands a test of his loyalty (while dangling the opportunity to become heaven's hero over his head like a tasty carrot) Gadreel refuses before even knowing who Metatron wants him to hurt:

METATRON: No, I mean REALLY sure. We have enemies who pose an imminent threat to our effort. They must be neutralized. GADREEL-IN-SAM: Slain? METATRON: In a word. GADREEL-IN-SAM: That... That is not who I am.

Gadreel proceeds to do several things he shouldn't do, but Metatron also lies to him at various points about the true nature of what he's doing because Metatron knows he can only push Gadreel so far before Gadreel morally objects. When Gadreel realizes that Metatron orchestrated the deaths of several angels he brainwashed and that he's going to hurt humanity, he accepts Metatron's true nature—that he isn't God's representative and nothing he's doing is righteous—and defects. After being wounded by MoC Dean, Gadreel tries to stop Cas from wasting grace healing him:

GADREEL: Please. I'll leave you alone, I swear. CASTIEL [reaching out to heal him]: We're not here to hurt you. GADREEL: No. Your Grace. Healing me will only weaken you. [CASTIEL doesn't even hesitant and instantly heals GADREEL]

Then in a last heroic act, Gadreel sacrifices himself to save humanity and the angels.

GADREEL: The only thing that matters in the end is the mission -- protecting those who would not and cannot protect themselves --the humans. None of us is bigger than that. And we will not let our fears, our self-absorption prevent us from seeing it through. Not anymore.

I MEAN?!?!?! It's just... so endearingly saturday-morning-superhero-cartoon style heroic. Knights of the round table heroic. It's endearing!

Even as he's dying to blow a hole in the cell to free Cas, he tells Hannah (who is keeping guard) in a superhero voice,