Through a somewhat random event, the Xcom base and all it's contents are summoned into the world of Nirn. After they had defeated the Uber Ethereal, they are ready, with their commander, to find a new purpose in Tamriel. And of course, evolve themselves like they have always done. Might make it a Mass effect crossover later on...

Harry is going through his normal extremely abusive childhood when a fire starts in in the Dursley's house. Harry gets trapped inside and in desperation calls upon his wild magic to get away. He succeeds and lands in a forest (Not the forbidden one) and is fed and protected by a local colony of Acromantulas who are enchanted by his wild magic. Dark/powerful/smart/Harry!

Bioshock/Fallout/Mass Effect crossover A malfunctioning lutece device causes Rapture to be frozen in time just as Eleanor reaches the surface. Rapture unfreezes just as the lone wanderer brings water to the wasteland. Eleanor rebuilds Rapture and sets out to unite Earth. Humanity then looks to the stars.