Why would we go around collecting tadpoles without a reason instead of ignoring them/killing them?
My guess is the first time we encounter another tadpole we'll get some sort of cutscene where our own tadpole urge us to consume the other tadpole to increase our power or something like that.
BTW I just saw that on the build people played on PFH the tadpole powers have an icon near the minimap, you click it put the bug on the trait and close the menu, that's it. No conversation, no nothing but the player already had a few perks unlocked at the time.
