formal if you presume on a quality that someone has, you use it in order to get an advantage
I shouldn't like to presume on your generosity.
phrasepresume upon presume on/upon sthBrE formal to use someone's kindness, trust, or friendship etc in a way that seem wrong, especially by asking them for more than you should: She did not want to presume on her friendship with Eve by expecting her to lend her the money.