My current headcannon is that the bird was flying across the multiverse, would up fighting me, and then kicked me down the hole when passing over. Doing so allowed him to escape, leaving Borusel to explore.
I also probably will share with you, as I have an idea for a photo involving The Doctor, Outer and Eliora, and Borusel. Just mine and RedLego’s OCs. However, doesn’t have to, due to the TARDIS being able to cross timelines and universes
Also, repost of the bird in question: https://youtu.be/nW20jwoMNkU?si=KaEyCW6q6aNbgMnf