I 100% agree with zhen's comment!

You should focus on ideas rather than centring your paragraphs on different characters (i.e.
don't do para #1: medea, para #2: jason, para #3: medea and jason).
So you could argue things like:
- though both are motivated by Ancient Greek values, it is their individual
response to such values that differs (depending on what values you want to focus on).
or...
- these values do not motivate medea and jason's actions; they are merely a
trigger for the pair's motives
This allows you to talk about medea, jason and other characters in all your body paragraphs, which is what teachers look for.
To answer your other question, have at least three body paragraphs. I see a trend developing where teachers are encouraging their students to write 4 paragraphs. In the end, it's what works best for
you. Four para's means you can explore the prompt further and unpack it deeper, but if you find yourself running out of time, it's better to have three paragraphs with more complex analysis than four paragraphs with really simplistic analysis under each argument.
Hope that helps
