Honestly, there are zero reasons as to why Jon and Martin would end up somewhere else together other than not wanting to give a completely gloom ending to jmart shippers (boring). Jon was stabbed, Martin wasn’t. Jon was the tether, Martin wasn’t. Jon was fully imbued with Eye’s power, Martin wasn’t.
Assuming Jon wouldn’t die “somewhere else”, which there’s no reason for, why would they have gone to the same place unless you get to travel with your stabber?
And in that case… d’you know who also got stabbed and whose stabber was right there? 😃