A defence filing before Tahawwur Rana's sentencing on Thursday describes him as charitable and kind-hearted.
It says he was duped into participation by a manipulative childhood friend, David Coleman Headley.
Prosecutors are asking a federal judge to impose the maximum 30-year sentence.
Jurors in 2011 convicted Rana of supporting a plot to attack a Danish newspaper that printed blasphemous caricatures and for supporting the group that attacked in Mumbai, killing more than 160 people.
Headley has pleaded guilty to laying the groundwork for the Mumbai attacks and testified against Rana.