Spanish, English, and some Japanese here. I feel it’s easier to pick up underlying patterns in vocabulary between languages which in turn lets me understand the written form of other related languages (Portuguese and Italian due to Spanish, some Chinese too). I don’t really consider monolingual to be all that different though I figure it can limit their ability to travel the world unhindered somewhat. I notice a very slight change in my personality depending on the language I’m speaking, like I get a little less patient when talking in Spanish and speak a little faster too.