Is this a run-on sentence?

"I thought about what he'd said soon I realized he was right."

I think it is. Just want to be sure.

Yep. You're right.

Thanks!

You're welcome.

Yes, the sentence you provided is a run-on sentence. A run-on sentence occurs when two or more independent clauses (complete thoughts) are joined together improperly without the necessary punctuation or conjunction.

To determine if a sentence is a run-on, you need to identify the independent clauses and check how they are connected. In your example, the two independent clauses are:

1. "I thought about what he'd said."
2. "Soon, I realized he was right."

These clauses can stand independently as separate sentences. However, in the given sentence, they are connected without any punctuation or conjunction, making it a run-on sentence. To correct it, you could add a coordinating conjunction (such as "and" or "but") between the clauses, or use a punctuation mark like a period or semicolon to separate them.

Here are a few corrected examples:

"I thought about what he'd said, and soon I realized he was right."
"I thought about what he'd said. Soon, I realized he was right."