He couldn't speak for her passionate prose since she doesn't seem to have written any, and he won't speak for her ability to make people fall in love with her... so before he gets there, he changes the topic slightly ;)
So far this is a very good comic! I think sound effects were used a little bit too much in the first couple of chapters but it seems you have corrected that. Wonderful, romantic, well written, there's really almost nothing bad I can say about it!
That head tilt with those words...I can almost hear the rustle of his clothes and the tone of his voice as he speaks. You have such a talent for evoking sensory detail (in my mind, anyway) with the smallest, subtlest touches.
The Beast is right, here - Beauty has been very gracious, considering the situation. I daresay a bit of his crush - or perhaps his idealization of Beauty - is coming through with how he compliments her, too. To be fair, they do seem to find each other's company enjoyable, so what he says is no less than the truth, but the words ring so sincere that I think they reveal his genuine fondness for Beauty.
Beauty's response to him is very humble - and perhaps also a little true, since the Beast doesn't get much company - but the humility is just as painful, because she's dismissing her own value again. The Beast is right in that she compares herself to others too much - it's almost impossible to be happy with yourself when you do that. However, given how young Beauty is, I can understand why she has that mindset; even adults struggle to overcome it.
Now when the Beast discusses finding comfort in one's role - and in having others know it - is he speaking of what he experienced in his past as a human, or is he speaking about his role as a servant to whoever holds his contract? Him discussing not having siblings right after that makes me lean towards him talking about his human past in this instance. The question is, was his role that of a prince or something else...?