Or, love in the Whoniverse, and specifically in DWAITAS.
Not even starting on the origins of Valentine’s day, it’s all too weird.
“Is there a lot of this in the future?”
“It does start to happen, yeah.”
The War Doctor asking the Eleventh about kissing, studiously ignoring his immediate predecessor and Grace, Day Of The Doctor
Love can lift you up, knock you down, inspire you, break mind control, raise the dead and defuse android bombs. There’s no Trait for it, but it could do with its own category for Story Point expenditure. Most of all, it can really drive a plot.
Do your characters find love, with other PCs or with NPCs? A connection of this level can be a great source of Big Emotional Episodes. It wouldn’t suit every game, but it can certainly add to one if it doesn’t become too scene-steal-y. Easier with, say, two players around the table than six.
And love that only involves NPCs can be a great plot device as well even if the players don’t get mixed up in it directly. Could the travellers save a pair of star-crossed lovers, or stop someone messing up the space-time continuum in order to get a first date to go well?