Stranger help?

._.

As long as he doesn't send you suspicious links, he's harmless ;)

Ask him why he added you? That can't be too much of a leap in logic...
If you are smart about it being randomly added by someone cannot hurt you in any way.

Too many topics about accidentally added Russian, what love is.

There are steam profiles of real people and also phishing bots.
There are some red flags (although not actual proof) of a bot.
Like no played game, low Steam level, private profile, people writing comments of "phishing or bot" in the profile,
and adding people for no known reason and with no talk whatsoever.

In the past 3 months I blocked dozens of accounts like that, they just add you and send a fake link for a trade or something similar. Phishing bots.

If thy don't send you link, thy is fine.