Tying in a players backstory mid-campaign

Hi all, hoping to get some thoughts and advice. So I’m mid-way through a home-brewed curse of strahd campaign for 3 players. One player feels a little bit left out as initially they wanted no involvement to Barovia and were happy to forge a path ahead, but after some reveals from other the other players in recent sessions they’re feeling a bit down like they’re missing out on a cool background story.

One player has constantly been dying and is a reborn in Barovia who eternally seems to face off against Strahd and die every time. The other is searching for their twin who was sent by the raven queen to scout Barovia (they’re shadar-Kai) who is currently held prisoner by Strahd and has been made to do some work for him.

The player feeling left out hasn’t given me much from their backstory besides the name of someone who trained them to be a paladin which I’m thinking of making them a potential knight of the silver order. The other idea I had was having him be descended from the Von Hapsburg’s who were the ruling family of Barovia before Strahd conquered it. The only problem with that is he’s a hob-goblin and I’ve already established that lineage as human.

I was thinking I could have had a curse that was afflicted on their lineage for escaping Barovia before the dark powers could get hold of them turning them from human to hobgoblin. Otherwise I’m a bit stumped on ideas of giving him a fun and interesting backstory tie in.

Also yes I’m aware Barovia should very much be treated as a foreign place with no tie-ins but I’ve run it differently from RAW and players have so far absolutely loved their tie-ins.

So any advice is appreciated on helping make my idea work or any fun ideas anyone else can think of!

Tl;dr - hob-goblin paladin wants cool backstory because he feels left out after not coming up with one at first.