Sentence pattern 10 and 11

Sentence pattern 10: Interrupting modifier between
subject and verb, using two:
Commas (,)
Dashes(—)
Parentheses (( ))

Ex.: American fast food is very popular and steakhouses (not to mention McDo and KFC) are in most countries.

10 a) Using a full sentence: a statement, question or exclamation (particularly with the dash or parenthesis)

Ex.: Narcissus ignored Echo so completly (how could he? she was such a lovely nymph!) that she faded away.

Ex.: Narcissus ignored Echo so completly (he was so stupid) that she faded away.

The statement, or question, or exclamation in the parenthesis is a lower case. So it is not capitalized and there is no period. The only punctuation would be to express the intention (excalmation mark, question mark.)

Sentence pattern 11: Introductory or concluding participles

Ex.: Being for the benefit of Mr. Kite, there will be a show tonight.

Put extra attention to the subkect. The concluding participles have to refer to the subkect of the clause.
Walking on stage, the spotlight focused on Maggie. The spotlight isn't waling on stage, Maggie is, but the subject is the spotlight.