The Luxon canonically has the ability to create a new soul and people who are either chosen by it or fuck in front of a beacon or both? (unclear) can be impregnated with that soul. Leylas/Quana have a child this way shortly after the events of the show in the Bright Queen tie-in comic. Somebody PLEASE make this happen to an m9 member of your choice.

maybe Jester's comments about "needing to make lots of babies" get taken literally
maybe Caleb gets "rewarded" for being the one to hand the beacon over
maybe this is post-canon!Essek's complicated ticket to get back in the Dynasty's favor
maybe literally any of them had a casual ONS near a beacon and got unlucky

whoever it is, just give us some drama + whatever pregnancy kinks you desire + the nein being a bumbling group of surprised co-parents