Lucius was a lot of things, a father, a lord, a pureblood, a Death Eater, but at his very foundation he was just a man, a man with needs and desires. It was important to note though that Lucius was a Malfoy, and that Malfoy's always get whatever it is that they want. They accept no less than what they believe they deserve and Lucius believed that he deserved a lot after his sacrifice in the war. While the ignorant wizarding public thought him to be nothing more than a filthy Slytherin Death Eater the truth was that Lucius Malfoy pureblood supremacist was in fact a spy for the light side of the war. It wasn't a truth that many would accept due to the soul destroying actions he had participated in during his time under Lord Voldemort. He had been following the mad man only as a result of his mother who had forced him into the man's service upon his father's death in the hopes of holding onto their position in wizarding society with a female acting head of the family. When the time came that he was able to take control of the family he had already been pledged to the Dark Lord and had taken his mark. He was trapped, it was obvious to him even at seventeen that the only way out of Voldemort's service was death.
He had resolved therefore to make the best out of a bad situation and ensure the continuation of the Malfoy line. He had gone to Albus Dumbledore and offered his services as a spy believing that such association would afford him legal protection for the actions that would be involved with being a Death Eater. Unfortunately that hadn't worked for him, although Dumbledore was more than willing to accept his services he wasn't willing to speak up for him once Voldemort was killed, insisting that Lucius keep his cover for when he returned. Lucius had instead had to plead imperious to get off of the charges against him. It almost hadn't worked and his reputation and that of the family was stained, not to mention the fact that he only just managed to stay out of Azkaban. Now though he wasn't going to be pushed around for the purpose of the light, he was sick of being their scapegoat. From now on Lucius was going to be in charge of his own life and safety; he refused to rely on Dumbledore any longer. After all, it hadn't done him any favours during the first war. He was luckily in a better position than most would expect, especially when he was being publicly accused of being a Death Eater.
Fortunately he had spent a great deal of time in the years between the two wars securing a base of influential friends. His wife Narcissa had been instrumental in helping him secure some of his friendships; she had used a lot of the Black families' contacts to put their family in a better position politically. He had to admit, even if only to himself, that marrying Narcissa was one of his better ideas. She was of the same mindset as he was when it came to muggles, neither of them were happy about them finding out about the wizarding world as a whole, but they didn't want to slaughter them all either. Their views were in line with those who were neutral, but as Lucius had already been bound to the Dark Lord and Narcissa was a Black, neutrality wasn't a path that either of them could take. Instead they had chosen to hide in the shadows of the light, hoping that when the war was over that they could move into more neutral territory and live how they wanted to. There was no love between him and Narcissa, but they had a strong bond of friendship that had made their marriage of convenience bearable for both of them.
However, now that the war was over, his mother was dead and so was Voldemort, with no chance of resurrection this time, they could divorce and go their separate ways. They had spoken about divorce often, before Voldemort had returned and the second war had kicked into full swing, but they had stayed together ultimately to help each other survive. Narcissa would never have been taken seriously by any of the men in Voldemort's service if they were divorced and the chance that she may have been reduced to the role of a plaything was too high to even consider a divorce. The fact that Narcissa was able to hold him back and calm him some was the one of the other reasons they had stayed together, she was very important to him keeping his cool when his colleagues had invaded his home and set up base. The last reason for their continued marriage had been for Draco's sake, their son had enough to deal with, the guilt of having almost taken a life, having allowed Death Eaters into the castle to attack his schoolmates, and the strain of having to sit through dinners with both his Aunt Bellatrix and the Dark Lord, no they had held off for many reasons. Those reasons were now obsolete and they were both free to pursue what they wanted, or rather who they wanted.
Narcissa had left almost immediately after the ink had dried on their divorce parchment, going straight to France where her lover awaited her. She had been in love with Markus for years and Lucius would not have done anything to stop them from being together. They had always been discrete with their liaisons and never brought shame upon the Malfoy name so why should he have cared really, except to know that his best friend was well cared for. They hadn't seen each other since the Dark Lord had returned though, Narcissa unwillingly to leave either him or Draco when the mad man was alive once more.
Lucius once she left began looking into other areas of interest. He had taken a few lovers over the years since Draco's birth, but none had ever held his interest for long. He knew Narcissa had despaired of him ever finding someone that could keep him occupied for more than a month, but he had found him. He was a puzzle wrapped in an enigma, every time Lucius thought he had figured the other man out he found something else out about the man that confused him even more. What he did know though, was that he wanted that puzzle to be his, unfortunately there were a few people and things in his way, but they could be driven off and any other problems could be dealt with.
He supposed that his biggest problem was the other man's girlfriend, well that and the fact that the other man had shown no indication of being anything other than one hundred percent heterosexual. He was Lucius Malfoy though, if anyone could seduce the other man to his way of thinking it was him. Harry Potter wouldn't know what hit him, and Ginny Weasley had no chance. Malfoy's always get what they want and he wanted Harry.