If you are a bear man with a bow going for some hunting and you meet a bear man with a bow going for some hunting...... and HE run...
That's prolly a possible new friend 'cuz he's scared like hell (as you were), so chase him and try to talk with him!
But don't force him to kill u, one can never know. XDD
Aside from few funny experiences i had, you can easily trust anyone when you log in an alt, but keep in mind some stuff.
Flame General Schema:
"You're walking with you main and you meet a noob/pro player."
[Enter mode: DANGER 1] - Save your main, log off, run, whatever is usefull but Not show where you live if possible. AND if they wear bunny sleeps, always run.
"You wanna know if they are friends..."
[Choose1: SacrificableAlt] - You login your fresh walking meat called "KillMeDude" and go to make some friend. You can't lose anything and you act really relaxed, this will help to not being hostile and not bring hostility against you. Also you can laugh and so on and often also evil peoples likes to play with matue mind dude.
[Choose2: Hiding] - If you log in an alt this mean that you live near, so that man will know that there is a living settlement near. This may be dangerous if your settlement is too much near, or may not. A foraging evil man that acts friendly may decide to change his day routine and raid you few hours later.
The main idea is to not forage with your alt.
So, basically, don't play like me. XD (i don't have time to grow a decent alt

)