Horace wrote the line brevis esse laboro, obscurus fio in De Arte Poetica Liber. I want to use the latter half of the phrase, obscurus fio, as a song title but I'd like it to be in the form of I am becoming obscure rather than just I become obscure. Would a different verb be used, or a different form such as factus? I'm not sure what to do with fio because it's irregular. I assume what I'm looking for is a present participle.
The present tense includes both general action and progressive action. To say "I am becoming obscure," you would still use the present tense. Using the present participle plus esse is not a Classical equivalent to a present progressive in English.
Also, fio doesn't have a present participle, since it is functionally the passive of facio. See you can see the forms it does have here.