Compare "Frankenstein" and "The Handmaid's Tale"

I found it quite difficult to find many interesting common themes between these two.

Identity
Rebellion
Mirrors / Reflections / Doppelgänger
Loneliness
Biblical references

Are there any more?And please add any ideas and thoughts for one or both the texts and their themes.

Also, how would i start a comparative essay on these two? (Interesting, which gets the reader?)

Thank youu