The Doctor waves him off a little to slow him down. "I don't know everything. I travel the whole of time and space, things get a little confused for me. And I've been away a long time. But there were natives here, when we all first started showing up. If they're not here any longer, I can't say."

He closes his eyes in thought. "First hostile species. I suppose you could say that. I mean, we've had hostile individuals show up before. But an entire species? No, this would be the first..."

He pales slightly. 😱 "Could mean the barriers between the universes are breaking down further..."

And if those disappear completely.... it would be bad.