That is a v good question! Tbh I'm very open and flexible person when it comes to various roles in fanfics and I read Mattael in various combinations.
I think the most popular option I stumble upon is them being both betas, so that's my first association. But I could also see Maet as alpha or Tael as omega. And because I'm a sucker for non trad dynamics and reversed expectations, I think beefy omega Maet would be also cute! (Unpopular opinion, I know)

I don't think I would see Tael as alpha as my first or second choice, but I'm always one good fic away from being persuaded 👀