Grammatically, the interrobang (‽), or more commonly written (!?) or (?!), should never be used in modern writing. The only time it commonly appears is in comic books or cartoons as a visual indicator of a strong questioning emotion.

Artistically, it could be used very sparingly to emphasise the same emotion in writing.

However, it is such an obscure punctuation mark (the original version is only available in a few fonts) you run the risk of confusing your readers and breaking the flow of your fiction—anything that throws your reader out of your fiction world is bad, in my opinion.

Much better, in my opinion, to use words and description to convey the same meaning and emotion, i.e show the emotion rather than rely on obscure grammar to do the job for you‽

Nick