
maybe rum meant the selfish way ginger acted like, or that rum knows ginger is not suited to be an angel so he tells him that even tho he knows he is a mix as if telling him *bae you are more to the demon side so let's finish this and head to bed* haha sorry . the mon and mananana thing , i've thought about it 4 so long but still have no idea

This is kinda long, hope it helps...
On the infirmary, Rum and Ginger are talking about how they grew up together. Ginger believes that he's still not an adult (he's still clumsy, selfish and he do what he wants). Since angels and demons doesn't really age that much and it looks like they're all in the same age after growing up, I think it's the maturity that we have to base what their age is. What you can consider adults are Mono, Monday and Baron. Observe the way they act and decide on things. They're duty oriented, overthink things and worry a lot. While Ginger and Rum looks like they're on their way to adulthood cause they start to think about things. While Mananan as the author describe him, his only coming out of age. You're right, Ginger hasn't decided yet if he's an angel or a demon. He wants to be an angel because when he and Rum are kids, Rum says that he likes angels. But Ginger's attitude is more demon-like. Remember? Demon are define by their instincts. That's why we see Ginger turning to demon instead.
Ginger was "the rumored hybrid" because he really looks like an angel. If you remember, Ginger's family lives in the demon's neighborhood. So I believe its a rumor between demons.
Mananan accusing Monday about not being a dark angel -- I believe he's referring to him being hybrid. Instead of using the word hybrid, dark angel was used. Mananan discovered that Monday and his father (Baron) went to the same school. It's a school for angels and even though you're a hybrid as long as you chose to be an angel, you can go to that school. Apparently, Monday chose to be a demon instead after graduating from school. (Mono said that when they reunite he was already a demon).

i always search for your comments here too lol your theories and all are great tho
Ok boys and girls!!! I have a question (seems like we all have questions when it comes to this series) anyway! I’ve reread all chapters many times but one thing I don’t get is in the first season and rum and ginger are in the infirmary ... rum says “but you are an adult and you are a demon” can someone explain... I thought ginger still hadn’t picked either .. (in season 2 as well) also how do they become “adults” any way like when rum says “will I have to become an adult on my own?” AND ginger is treated like a unicorn by Lego who calls him “the rumored hybrid” but Monday is one too........ one last thing what did mannan mean when he said to mon “so you lied about being a dark angel”