The affix -qati- is attached to a verb to indicate someone or some people who do something with someone else:
|pi + qati = piqati
|someone with whom one meets
-qati is often followed by the affix -gi- meaning to have, which is in turn followed by a double verb ending:
|Susi is my classmate (literally, I have Susi as a classmate).
|He is talking to him/her.
|She is sewing with her.
|Can you meet with me?
|Do you work with Taiviti? (literally, do you have Taiviti as a co-worker)?
With regard to the last example above, when answering a question like this, the construction is usually simplified when you answer:
|Yes, he is my co-worker.