Perfect
Let it not be said that Hatake Kakashi lived a perfect life.
There were many things the man famed as 'The Copy Ninja' regretted. Many things which had caused him to distance himself from others. Many things that made him wish that he lived in a perfect world.
In a perfect world Uchiha Obito wouldn't have been crushed by a rock. In a perfect world Nohara Rin wouldn't have jumped in front of Kakashi's Lightning Cutter. Minato-Sensei would still be alive. The Uchiha massacre would have never happened. The war which claimed so many lives would have been avoided.
But in that same 'perfect world', the group known as Team 7, the Sannin reborn or the second coming of the Sages sons (depending on who you listen to) would never have happened. Uchiha Sasuke would never have had to strive to get stronger to kill his brother. Uzumaki Naruto would never have had to shoulder the burden of Jinchuuriki and saviour. Haruno Sakura would never have striven to get stronger to prove herself. Team 7 would never have splintered, only to reform better and stronger than it was before.
So maybe Hatake Kakashi didn't live in a perfect world. His world was filled with flaws. But it was all the more perfect for it.
Hmmm Kakashi's not someone I've really written before. I actually think he's an interesting character to write. Might be seeing more of him.