This book is loaded with this, in both storylines.
In the main, real-world one:
Michael constantly notes all kinds of physical details about Francis - the sun on his hair, stuff about his hands, his confident aura, his posh accent - seriously more-than-treading the line into Female Gaze.
He spends a lot of time feeling insecure about their (very close, personal) friendship.
Michael is very possessive about the imaginary country they create together - most of the conflict comes from his furious reaction when he thinks Francis told someone else.
They spend loads of time together in some locations of varying romantic level (including a castle).
At the castle, Michael falls asleep and panics when he wakes up and Francis isn't with him, thinking that he had left (he hasn't). It's reminiscent of someone who thinks his lover is Not Staying for Breakfast.
Michael gushes emphatically over Francis' assorted mapmaking skills.
On the subject of Francis's supposed betrayal: "...Why didn't you take a few pornographic photos of yourself and hand [Francis] the negatives, while you were at it? Or handcuff yourself naked to a lamp-post and give him the keys?" This is then followed by "He'd rather he was chained naked to a lamp-post."
It's possibly not one-sided, either, since although we don't get inside Francis's head, he clearly trusts Michael deeply, and has some rather... interesting... lines such as "For you, Michael, anything." Not kidding.
Neither of them shows any interest in girls, and Francis is even gay, just to cement the Yaoi Fangirls' dreams.
Francis holds Michael's wrist while staring into his eyes, and Michael reflects on how he should pull away because it's like Francis is coming on to him, but he doesn't pull away.
And as for the other storyline...
The two boys become friends after Columen argues Argent off a battlement.
Argent also notices a lot of physical details regarding Columen.
Columen explicitly takes Argent's face in his hands and calls him beautiful.
Argent says a particular delighted expression of Columen's "took his breath away". That has to be canon.
Note that Michael is making up the Evgard story, so all the Ho Yay in this storyline is coming from his imagination. It's all too easy to assume that it's a case of in-universe Author Appeal and/or Reality Subtext.
Wordof Godsays that Michael and Francis will probably end up together some point in the future.