History is written by the victors. Many consider history to be fixed but it is ever changing based on who writes it. Allow me to give an example. Consider our grand epic Ramayana, hailed as an epic magnifying the victory of good over evil with Ram hailed as the paragon of virtue and Ravana as the supreme embodiment of evil.
Say Ravana had won, this is the tale that we would have heard.
Ravana went to Sita's Swayamvara, he truly loved her and she him. He strung Shiva's bow and when he let loose an arrow the bow broke into two. The court was aghast at this display of strength and valour but the Lord Janaka, Sita's father intervened. He said that a man from afar could not marry a maiden from his kingdom. Ravana being the man he was, respected the wishes of his elders and acceded for he did not want Sita to fall into disgrace in her own kingdom.
Eventually Sita was married to Ram. He happened to be a drunk and a wife beater. Despite being the eldest son his father decided to hand the kingdom over to his younger brother Bharat because everyone knew that Ram could not be king. Ram of course was not happy with this development and staged a coup with the help of another of his brothers Laxman. Eventually Ram and Laxman were beaten and banished.
Sita could not take the life of the forest anymore. Ram was losing it by the day. She begged and prayed to Ravana to come and rescue her from this tyranny. Ravana who could not bear to see his maiden in distress took her away in his Pushpak Viman to Lanka with the help of Marichi who distracted Ram by , disguising himself as a beautiful deer which Ram wanted to skin and make a garb out of.(Ram could not leave an object of beauty all alone)
Ram of course could not bear this. His pride was hurt and he wanted his wife back not because he loved her but because he could not bear the disgrace of losing his wife after all that had happened. He needed an army and he would get one at any cost. He helped the Vanar Sugreeva, who wanted the usurp the kingdom from his elder brother Vali. Sugreeva challenged Vali to single combat and Ram happily shot Vali in the back while the two of them fought their private battle to decide the kingdom flouting every single warrior code.
With Sugreeva thus bound to him he had an army. He worked them to the bones constructing a bridge to Lanka. Ram also sent one of his most powerful warriors Hanuman to lay to waste the pristine city of Lanka even before the battle had started not even sparing the civilians. Ravana sent his son from another marriage Indrajeet, who killed Ram and Laxman in a fair fight but they were bought back from the dead using the darkest of magic. Indrajeet was then killed by stealth while he was worshipping lord Shiva for no place is sacred to the damned. Kumbakarna Ravana's ever asleep brother was killed in his sleep lest he wake up. The youngest brother Vibhishana, always jealous of Ravana and his abilities was promised the kingdom in exchange for his help. In short Ram left no stone unturned to gain victory.
Finally the good king Ravana decided to take matters into his own hands. He called out Ram for a fair fight. Ram had no choice and after a lengthy battle was killed. Ravana the merciful let the survivors travel back to their homelands and even provided them supplies for the long and arduous journey. Ravana and Sita lived happily ever after. Ravana would have been hailed across all future generations as a saviour, probably as Maryada Purshottam and we might even have had a festival celebrating his victory over evil.