Malfoy was shaking and said, "He's my son."
"I know but...."
"I bore him," Malfoy whispered. 
Harry blinked. "What?" It wasn't computing. Then he looked at Malfoy. "Oh... are you... um... trans?"
Malfoy rolled his eyes, showing some of his old self. "A potion can make it possible for men to have children, Potter."
Harry was dumbfounded. After thirteen years of knowing about magic, it can still surprise him. "Oh... umm... sorry, alright... so who's the other father?"
Malfoy tensed up and looked at the table. "I don't know."
Harry blanked as he had an epiphany. The backhand comments were finally clicking into place. He knew what happened.
"It was my punishment," Draco whispered, his eyes going still. "For being a... coward. For refusing to kill... Dumbledore."
Harry's heart seared with pain, and he had to refrain from trying to hug... Draco. Harry was still missing something... or he needed the confirmation. He wasn't sure if he should press Draco or not. "I see...."
Draco's tone was bitter, and he stared blankly at the floor. "Since I was a coward... I wasn't useful to him as a man. He ordered that I was to lie on my back and produce like the other women." 
Harry's lip curled, and he growled, "That sick fuck."
Draco nodded and seemed resigned. He stared at the wall blankly and murmured, "He ordered Snape to brew it and said I was... available for anyone to use... until I became pregnant. Not that it stopped them."
"I'm so sorry, Draco," Harry said, as Malfoy wiped tears out of his eyes.
"I don't know who the father is. They all did it... many times. They brought me to the meetings as entertainment. So, all the Death Eaters and their friends and family knew what I was... what my punishment was. That's where the nicknames came from."
"I'm so sorry you had to tell me it, Draco," Harry said, trying to keep the tears out of his own eyes. "The Aurors will still use Veritaserum on you, but they will hide that knowledge. Sympathy for Death Eaters is not allowed."
"As long as my son is okay, I don't care. It doesn't matter to me how he was connived. He's such a sweet, innocent child. I didn't teach him to hate people, or about me and what happened, I swear," Draco said, his emotions getting to him.
"I believe you, okay? I won't let anyone hurt him, so breathe...."
"He was the only reason I kept going."
"Draco... calm down. He needs you. Stay with me, okay? Our time is running short. I need to ask you a few more things. What about your parents?"
Draco's jaw clenched, and he looked both mad and ashamed. Harry could guess that the split hadn't been amicable.
"I'm sorry. I need to know," Harry whispered.
"My father gave up on me when it happened. My mother tried to help, but she picked him in the end."
Harry shook his head. "She refused to tell me what happened, but she seemed sad about it. She'll be in Azkaban for several more years, if you didn't know."
Malfoy shook his head. "No, I didn't. Owls can be tracked. I put up wards to repel them. Is my father in prison, too?"
"Yes, for life."
Draco nodded. "Good."
"So... they'll ask... but how much did you have to break the ISS?"
Draco shrugged. "Nothing blatant that I know of. I only cast wards and Repelling Charms on my things. I taught my son out of sight. I never had to Obliviate anyone."