I made a thread on this a few days ago and i found out that it seems no one knows for sure.
Some people claim, no they don't. Link articles and such. And claim their old character that they met at lvl 10 is now getting one shotted by everything at lvl 50.
Others claim they do level up. Pointing out other articles saying they do. And claim their old character that they met at lvl 10 is still strong. And upon opening a console command to check their companions level, they are usually around 5 levels behind at lv 50.
In conclusion i didn't really get anything out of my thread, other than it seems to apply for some, and not for others. As well as there is numerous topics supporting both sides of this. I don't know which is correct, or which will work for you.
Just thought i'd share what i found on my thread that had this same topic.
Actually, thank you very much for your input
I too am realising now that no one truly knows for certain esp. with all the contradicting 'sources' out there.
I only wish Bethesda actually read these forums and could answer for us, as this would assist many players out there (you and I included) in our enjoyment and playstyle of this game, shame really
