Answer:
Hovstad and Billing are both hypocrites, that is the overall summary of their characters.
They both appear to support Dr. Stockmann and his work, but they are later revealed to each have their own agendas separate to what they pretend to believe in.
Step-by-step explanation:
Hosvtad is the editor of The People's Messenger, a newspaper in the play "an Enemy of the People". He has the reputation of being the liberal of the town and wants to starts a revolution. Initially his ideas appear to be genuine, especially as he offers to publish Dr. Stockmann's controversial findings. However, it turns out he only wants to further his own agenda (i.e increase his paper's circulation) using the findings, instead of using them to bring about real social change.
He is revealed to be hypocritical when he turns on Dr. Stockmann and changes his beliefs and what he portrays in his newspaper whenever public opinion changes.
Hovstad strengths and weaknesses both take root from his newspaper.
Billing is the sub-editor the newspaper, he mirrors the ideas of Hovstad with a few personal opinions of himself. He criticizes others for being conservative and claims to be a radical progressive, he is later revealed to be a hypocrite of his own ideals when he applied for a job within the government he supposedly hates.
They initially supported Dr. Stockmann but turned on him later when they found that his opinions will not be popular with the public.