I am writing a story about an immortal that was born at the end of time and lives backwards to the start of time. He meets a girl at the end of her life then falls in love and goes with her, through her life. Can you help me by finding a word that means that "going past one another?"
Since your story is fantastical, I humbly suggest you create your own term. Something like "retromeeting" or "temporal encounter." You're a writer, creating an alternate reality, so use that creativity! :-)
I'll throw one more at you. This is a real phrase:
It's usually referenced in terms of audio engineering. But if you think about it, humans' atoms vibrate at assigned frequencies. What if two distinct frequencies were to overlap?
And hey, it sure sounds techno-cool.
Let me know if it inspires your creative juices...
EDIT: not sure why somebody downvoted me...obviously a word doesn't exist for the scenario the author described, because it's a scenario and an action (meeting someone while going backwards in time) that isn't possible. Rather than downvote, I'd encourage you to attempt to answer the question, as I did by offering up two self-created terms which accurately depict what the poster requested.
Their time-lines (or lives) intersected.
Quoting Line-line intersection on wikipedia:
In Euclidean geometry, the intersection of a line and a line can be the empty set, a point, or a line.
In you case their joint lives could perhaps be a line intersection?
I realise this doesn't get across the time travel in opposite directions part!