At the end of the day I think for the audience you’ll see some changes but not so much for Magnus. Magnus goes through many changes throughout decades or even year or even by the minute [or] what seems like the minute is a blink of an eye for him. So you’re definitely going to see some changes as far as mood and even looks. Since the first season you’ve seen him change within days of looks and he’s a very tempered, half-human, half-demon, and he’s also very impatient in the sense that he gets bored really easily. So I think you can expect definitely some different moods and changes and looks from Magnus and to not say that he’s out of character but more so that he likes to spice things up a lot.
Harry talking Season 2’s Magnus during ‘Single By 30’s Press Day, via TVInsider.