The 'poem' on that poster does has to do with things Dulce went through when he was younger, I will add much more about that in the future (since it is actually one of the two main things the story is actually about) like I said before, there is not only that one poster but also the secret messages on the "keysmashing" (because it means actual stuff and it is not just random) and in some images with it it might be hard to see well/kinda long which is kinda on purpose since it has some darker stuff, the poster is more mild compared to these but it's about the same trauma.
I'm glad you are fond of him! It is true he needs some love, though I don't know how well I could answer that question without spoiling much, he is practically the main character of the game so you will see much more of him and get to have a much deeper bond, probably much better than just "romancing".
Dulce is literally translated to "Sweet" (sometimes even "Candy") in spanish (he is mexican) and is more commonly a girls given name, but the word itself is masculine, so I think it fits him well. He is also called Salvador which translates to "Savior" and is a last name and given name for boys (so he'd be "Sweet Savior" which is a bit ironic, thinking about his backstory he'd be more of a bitter victim) though I didn't include that in the game so far and is only in one single file, just a fun fact.
