We have three separate storylines here
First of all Dean and Ketch have jumped through the rift and Dean does his best to dump Ketch straight away. Ketch is not really into that since he and Mary had a thing and he’s also really looking for a redemption arc after the conscience pricking things Asmodeus told him last time
Also it’s quickly apparent Dean doesn’t really have a plan beyond “go through rift and rescue” while not knowing where he’s going or what he’s doing. They run into a guy with nasty poison weapons who nearly kills Dean (Ketch saves him and Dean kills the attacker) leaving Dean all nastily poisoned. It’s a horrible poison used by the Men of letters so Ketch knows the antidote while we get another round of oh-what-a-terrible-person I am. So much that he might as well be waving a huge Redemption train ticket
They find some angels executing human resistance members - Ketch stops Dean from charging in all suicide style (Ketch at least has some grasp of the concept of tactics; Dean is just a weapon. A loose cannon). Which gets hard when one of those resistance members of Charlie
Oh… oh there’s a lot of complex feels here over Charlie. Part of me is actually angry that they brought her back because it gives them a chance to kill her again.
They take Charlie for interrogation while Dean allows his entire plan, such that it is, to be derailed in order to save Charlie instead, taking the angel killing bullets from the man they killed in order to raise a rescue
Ketch isn’t entirely happy to be derailing everything they’d planned for, all their goals in order to rescue some parallel world stranger but since Mary and Jack are no longer imprisoned by Michael but are with the Resistance, Charlie may be key to finding them. Also he’s looking for any redemption right now - hey might as well cling to Dean’s as anything (since Dean is definitely looking at redeeming himself for failing to save her the first time).
After all this Dean is not in great shape and they don’t have much time - so it’s back to the portal to arrange another visit. Ketch and Charlie decides to stay behind. Ketch because REDEMPTION TRAAAAAIN and Charlie because she’s a Resistance leader and you don’t just run out on your people when you’re a Resistance head.
But Dean doesn’t have a lot to return to
Castiel (not happy Dean ran off alone) joins Sam in trying to heal Gabriel (and seems genuinely shaken that the Archangel is in such a pitiful state). Castiel isn’t exactly gentle in his attempts to heal Gabriel, reminding us again that angels are not gentle kind creatures.
They try several ways to heal him and seem to make a breakthrough when Gabriel writes his story since faking his own death on the walls of his room (including that Asmodeus was the weakest of the Princes of Hell but became so much stronger with Gabriel’s grace), but he still fails to come back to himself. It’s only when Sam makes a convoluted comparison to his own experiences and how you all totally have a duty that they seem to get through to Gabriel - and he drinks his own grace.
Which is when Asmodeus arrives, attracted by Gabriel’s rekindled power. He easily knocks Castiel and Sam aside, holding them captive preparing to kill them - but Gabriel isn’t broken any more he has glowy white/blue eyes and awesome wing effects
And everyone knows that things are going to get Dramatic when the angels pull out their awesome wing effects
We are reminded that Princes of Hell are impressive - but an Archangel is still an Archangel. Charged up, Gabriel burns Asmodeus to death with a dirty look, a gesture and a snide comment about his terrible suit. Because, again, Archangels are top of the tree. Though I do question how Asmodeus managed to subdue Gabriel in the first place
That awesomeness done, Sam is all “yay we have an archangel now to help us rescue Mary and Jack and fight Michael’s invasion!”
To which Gabriel responds “lol nope” and gets the hell out of there. They point out he has a duty to his family, Gabriel has the excellent response that daddy dearest, god himself, has already bailed on this world so screw that.
Which is when Dean comes back hearing that they have no Archangel grave AND Gabriel has vamoosed so they can’t open the portal. Dean does not take this well.
And thirdly we have heaven, where Lucifer is finding things very very boring while Anael is getting steadily pissed. She supported Lucifer to take over heaven to make changes, to break open the stifling hierarchy, to make things better. While Lucifer took over heaven because he has extreme entitlement issues and wants everyone to worship him. He’s also miffed that the angels don’t bow and scrape to him like they did God - but as Anael points out, Lucifer just inherited this.
At Anael’s sniping he tries to listen to prayers but find them boring. He does intervene in an exorcism which is amusing but then kills the priests because they get all up tight about Lucifer being there and keep throwing holy water at him
After that token effort he returns to heaven and pouts because he isn’t worshipped and blames his daddy because Lucifer is all about his daddy issues. He decides a new plan: find his son and use his awesome power to change the world so everyone loves Lucifer
Anael is not here for this self-aggrandising bullshit and would like something more concrete from her leader. Especially when she learns Lucifer can’t actually create new Angels or give them back their wings as he claimed. She gets angry - he starts to strangle her to try and intimidate her by force
Which is all he has - force and power. He has nothing else to offer. Anael walks out (but she has pushed all his sore spots about how terrible Lucifer is). I don’t think Lucifer leading heaven is going to last much longer