If Marvel depicts Dr M like how he was in DC, I would suspect it would be how Beyonder was shown originally, i.e. someone from the outside curious about how things work in the universe.. except Osterman would be more observant on some cases and directly changing the narrative on some stories.. He would more likely focus on Marvel earth predominantly... I would suspect he might have a special interest in Marvel's First Family and his interaction with Reed should be special..
That would be how I would see him set up, as being another real Beyonder type, and maybe would have a special interest in Hranklin Richards, or Spiderman, or even Cap America?