If you malign someone, you badmouth them — just like the jilted girlfriend who tells the whole school her ex has bad breath and head lice.
It's no surprise that malign comes from a Middle English word that means "to attack." Because when you malign someone you're attacking their character or reputation with a lot of trash talk. That would actually make it appropriate to then describe you as "a malign influence" — in other words, evil and full of malignant purpose.
