Could you please assure me that the Jesus that I meet in Revelation matches with the Jesus in the Gospels? He seems harsher.

I'm not sure whether this person wants me to assure them that the Gospel Jesus is the Revelation Jesus or that the Revelation Jesus is the Gospel Jesus.

It sounds like "he seems harsher" means they are inclined to think that the Revelation Jesus may not be the real Jesus? I'm not sure.

They are the same Jesus, I promise you.

One way to come at that issue is to say that when you look at Jesus describing the end in Matthew 24-25 or Mark 13 or Luke 21, the predictions that he makes are of him coming in the glory of his Father, and a great judgment happening between sheep and goats, and the goats will be sent into eternal punishment.

So, even though it's kind of shortened down, that is dreadful. That is horrific! Eternal is eternal, and punishment is punishment. And Jesus more than anybody in the Bible speaks of hell (Gehenna). And Jesus more than anybody in the Bible uses pictures for hell like "outer darkness" or "unquenchable flames" or "their worm does not die" or "weeping and gnashing of teeth." These are all, in the Gospels, Jesus describing what will become of those who, at his Second Coming, have not put their faith in him.

And so the Jesus of the Gospels is the one who speaks vividly, powerfully about hell. And the Jesus of the Revelation is the one who, at the end, says "The spirit and the bride say, 'Come.' Let him who hears, 'Come.'" Jesus invites us, "Let him who is thirsty come. The water has no price, it's free."

Jesus is presented in Revelation as the Christ who died for us, loves us, covers our sin, provides our robes made white by washing them in red blood. He is a glorious Savior, and we need him to be both harshly just with sinners, and we need him to be tenderly merciful toward those who repent.