The Escape

Loki escapes after the 2012 attack on New York, without the Tesseract, but away from the other Avengers and Thor.

Fastforward to 2016, where Stephen Strange is seeking help in Kamar Taj. Neither of the two expect to meet each other, but as faith has it (and the author) they encounter each other and both of them are surprised with their founding.

(Slow burn. Like, really slow.)