my favorite thought right now is right at the beginning so i can say it without spoilers!

Rikuo gets sucked up into the portal thing as he's leaving school and while he's wandering around trying to figure out where the hell he is he ends up running into his younger grandpa and recognizes him from paintings they had in the house of grandma yo and him so he tries to convince (who i've dubbed as) Prime!grandpa to help him but i firmly belive younger nurarihyon is a little shit and doesn't beleive a word rikuo says so he runs away. and then rikuo is like "well if gramps won't help me i'll just go home" and then when prime!nurarihyon gets home he runs to yo to complain about the "weird kid following me around" only to find rikuo in the parlor with her sipping tea and he points at him and goes "WHAT THE HELL ARE YOU DOING IN MY HOUSE??" and rikuo's smug bratty self sips tea like "bitch i live here too" except he's nicer as his human form and doesn't say 'bitch' specifically but you get what i mean XD

If you've ever had a sibling that enjoyed annoying you for zero reason and fight each other on sight but would also literally die for each other thats basically what i imagine their dynamic to be--and then that but x3 when rihan gets in on it too later down the line

my all time funniest idea is prime!gramps eventually helping rikuo find the yokai that brought him there and they think they send him home only for rikuo to end up slightly further up the timeline to when rihan was leading the nura clan and rikuo goes home from whatever random backwoods he ends up in after the magic fuckery expecting a kiss home from his wife (tsurara) only to get jumped by ao and kubinashi and he's just like "wait wtf????" and then still prime but slightly older grandpa pops out of nowhere and is like "RIKUO?????? WTF?????" and he just sighs cause goddamn it tails he misses his wife

meanwhile he's been gone from his actual timeline for like an hour

um . . . i have many more thoughts but yea this is long now hahaha oops