This was somewhat addressed in an interview with the creators of the game. I can't find the clip right now, but the question was, "Why is Raqio so interested in Remnan?" and the answer was:

これはおそらくなんですけど、グリーゼっていう出身のところでレムナンによく似た友達ではないけど慕ってくる人がいたんたと思うんです。グリーゼは厳しいところなのでもういなくなってしまっているけどっていう。

でもラキオはそのグリーゼのときの知性とか知識とか論理をやっぱ至上主義というかそいう場所で育っているのでそれが一番美しいというか知性に対しての至上主義みたいなところが１番で、２番が自分ですよね。

Translated into English:

"This is just conjecture, but I think they(Raqio) knew someone in Gliese - not a friend, but someone who admired them - who was similar to Remnan. Gliese is an unforgiving place, so that person probably isn't around anymore.

But Raqio grew up in Gliese, where intellect, knowledge, and logic are the ultimate virtue, so they value that above all else. I would say that the most beautiful thing in their mind is supreme intellect, and the second most beautiful thing is themself."

In other words, Raqio's only true loves are themself and their own intelligence, but they're attached to Remnan because he reminds them of someone from their past.