How about (for example?)
Don't Sleep, There Are Snakes: Life and Language in the Amazonian Jungle by Dan Everett and
The Education of Koko by Francine Patterson and Eugene Linden? I mean, aren't they essentially autobiographical? And they're written by linguists, so...Plus there are a number of books (and novels?) about
Bhartṛhari. There are also some in Malayalam at least about
Hermann Gundert, and there's
this about
A. R. Raja Raja Varma, who I think is arguably a linguist in some sense given that he basically wrote the first grammar for Malayalam.
EDIT: Not a novel, and not technically about a linguist, but there are two versions I know of an Indian story that goes as follows: Once upon a time, a polyglot entered an emperor's court and challenged the courtiers to figure out what his native language was and where he was from. However, he was so fluent in so many languages that none of the scholars at the court could figure it out. Finally, the emperor's favorite minister found out where the polyglot was staying, snuck in in the middle of the night, and surprised him somehow, causing the polyglot to cry out in his native language and thereby giving away his place of origin as well. Conveniently enough, the polyglot is never from a particularly faraway place, so the language is easily recognizable from the minister's perspective. (In fact, in one of the two versions I know, the language is the minister's own native language).
EDIT2: Also Panini is apparently mentioned in some Indian works of literature, though I'm not sure whether he's ever a protagonist per se. Apparently, the
Panchatantra claims that Panini was killed by a lion and that several other scholars (some of them also linguists) were similarly killed by wild animals.