"Modality", if it means anything, is complicated by mode degeneracy. The 7-note scale on D is D-dorian; the 7-note scale on D with B-flat is D-aeolian. A melody with only 6 notes of this scale, avoiding B/B-flat, can be assigned either to the dorian or the aeolian mode: The two form a degenerate pair, the degeneracy only being removed by the presence of the B or B-flat. When I invent melodies in the dorian mode, I make sure to emphasize the B-natural and the A <--> B-natural whole tone, to emphasise the melody's dorian character.

Likewise in G-myxolydian it seems possible to give a melody a myxolydian character by emphasizing C and F in certain ways before ending on G. A well-known myxolydian melody, Gregorian psalm tone 7, seems to do this.

But I don't see how lumping myxolydian character and dorian character under "modal character", though it may be logically sound, gets us very far in practice. Besides, as clare points out, a melody's major or chromatic minor character is just a "modal" as any other melody's "modal" character. Merely a different mode is used.

T.