That sounds like a great backstory! I think Umberlee might make the most sense, but Tempest would work okay. (
https://forgottenrealms.fandom.com/wiki/Umberlee)
They should probably be adding Umberlee in a choice, since she has one of the largest temples in Baldur's Gate.
The more I think about it the more it has this Vinland Saga feel with my Dwarf Tempest Cleric being basically like a viking in this case who found something tender to care for, but then had it taken away.
I also now imagine both my Dragonborn and Dwarf reacted to each other's deaths. Dwarf buried her body near the sea (or maybe send her body out into the sea, don't know how Tempest Clerics deal with this) while Dragonborn run away, having a Berserk chapter 90 moment as she couldn't bear even looking at his body. Also for Dragonborn I think of doing a roleplay where she resists her urges, but also shoves Tadpoles into her head, further encouraged by this Guardian looking like that Dwarf, she does it to escape them, to be free. A very tragic situation. While my Dwarf needs to deal with his self loathing and forgive himself as maybe that Dragonborn now watches over him and forgave him already while the Guardian takes her form.
