In the Old Testament, Satan is not mentioned as a person of evil. The OT uses the definite article, "The satan," as "the deceiver; the accuser." He is more like a functionary of God (book of Job, he is like a prosecutor bringing a case against God, but not like a demonic being) than an enemy. He's not portrayed as inherently evil. Other than in Job, there are occasional references for an adversary, but not a personal evil being we call Satan.

Jesus talks a little more about him. There is never a suggestion there that he is an enemy of God, but definitely is an enemy of God's people (and only in that sense hostile to the work and ways of God).

At Jesus's temptation, Satan, who is certainly real, doesn't show any power. He's all talk. Everything he does during the ministry of Jesus folds right into God's plans. It's not that he's God's functionary (he's not a minion doing God's dirty work), but he doesn't do much of anything in Jesus's ministry.

Then in the rest of the NT we hear a little more. He's a liar, dedicated to deceive Christians and non-Christians alike, working to our spiritual demise. The extent of his power is never explained other than that.

Even in Revelation he is mostly a deceiver. Obviously there's a little more to it, but we'd have to look at and discuss specific texts.

Whenever he is put up against God, it's no contest. For God it's like shooting fish in a bucket, or killing a mosquito on His arm. Satan is no challenge to him. For us Satan is a formidable opponent. We would have to talk about specific texts beyond my generalities here.

I ask because I hear a lot of "He ain't evil at all just a This and that, etc", So going off of the Abrahamic Lore which is provided and He is from, How Evil is He? What has He done aside from "rebel" against God?