Well, I'm leaving it in your hands to some extent here... Do you want Wilhelm to have killed her philandering father, or a philandering faerie impersonating her father? If you don't care, I'll make the choice, I just want an acknowledgement that you're leaving it to me, and that you don't object (too much!).
Hmm...well, she's spent the last 20-some years believing that she killed her philandering father. And it makes sense that it was actually a dark fae that she killed by mistake. I'm just trying to see the story in it (from a fae point of view, not a gaming point of view), since I think the Fae tend to play out stories or re-create some aspect of human existence.
Perhaps Hiltprant was faithful to his wife, but he was very good-looking so he drew a lot of second looks. So the dark fae maybe lured him into their realm to test his fidelity to his wife, while letting his doppelgänger have his way with anyone who wanted him to test their marriage in the mortal realm? And that it was actually the faerie that Wilhelm killed all those years ago?
Basically, with what's come out so far, I'm thinking more likely that it was a fae that Wilhelm killed and not his father. I'd say about a 70-30 preference toward the fae.
((This will probably transform the Dark Secret into a Plagued by Supernatural Entity flaw, or something along those lines, if you're fine with that.))
((Sure. I just don't expect her to be all "Yeah, when I was a kid I thought I murdered my father in cold blood, but we're cool now." 
))
"When father..came back, our brothers began acting much differently. Less well behaved and started causing mother and father untold misery. Of course, father knew why, they weren't his children, exactly, though they certainly favored him. He could never convince mother to return them to the forest, and so they did their best, but when they were old enough, father kicked them out of the House, and soon they were kicked out of the village altogether. We haven't seen them in many years. It will be nice to have you home for a bit." Hiltprant seems to be reaching to form a connection with Wilhelma or Wilhelm, as she prefers, he's never had any siblings to speak of, despite having three, he's never really known any of them.
[color=green]"So, all the children I know about," Wilhelm says as he looks at Hiltprant, [color=green]"Engelhart, Ava, Kirstyn...none of them were really Father's? They were by the faerie that replaced him?"
"So it would seem. We don't really understand it, mother, father and I, but that's what one of the Wizard's said. They said it might be related to how all the ladies of the village react to father, that it caused jealousy, or something? That they feed of the trouble they cause to those they torment. I think Kirstyn is a Witch now, one of the Wizards called her Mary Neat or something, I don't understand it all, myself."
[color=green]"Very interesting," Wilhelm says thoughtfully. "Mary Neat" sounds vaguely familiar, but he can't put his finger on it. ((He doesn't have Order of Hermes Lore, and none of the Mons Electi magi were Merinita. Although it's quite likely that the Durenmar Chapter House had one.))
[color=green]"You said the women of the village react strangely to Father? Or to the faerie that replaced him? How are they reacting?"
"Well, my experience is that the women all desire him. I'm unsure if this is a result of his time with the Fae, or..." he leaves it hanging, "But there are several ladies with husbands who are gone for whatever reason who ask father for favors to fix things around their homes. They make advances. And despite his politely declining, they never seem to stop, nor get upset. I don't know if this as it was before the Faerie, mother says he's always been like that and felt fortunate to capture such a handsome man, or if it's because his imposter has been with many of them, or perhaps a bit of both. Truthfully, they should retire away, somewhere. And father, well, father looks so very young for his age, perhaps a dozen years younger than he should look for a man of his age." Wilhelm gets the sense that his brother is giving him the unvarnished truth as he knows it, but much of it is second hand. Although, he has witnessed his father being propositioned, as he is often brought along to as a helper to his father's handyman...
Wilhelm merely makes the occasional mmhmm or grunt to show that he is listening. He finds this quite interesting, and makes him wonder. Is it possible that, although it now seems that he killed the wrong man all those years ago, that his real father may have learned his lesson somehow after all? Or has he gotten more conniving in his adulterous ways? He will still have to watch his father like a hawk when he gets home.
[color=green]"What about you, Hiltprant?" he asks after a while. [color=green]"You asked if you had any nieces or nephews. I may well ask the same of you. Are you married? Do you have any children? And what of our brother and sisters? Do they have families that I will meet for the first time?"
"I'm betrothed, we will marry soon. We have not been...sinful." He says almost shocked at the question, but then quickly softens when he realizes Wilhelm meant nothing by it. "Our siblings have been driven from the village, and besides the one who is a Wizard who calls herself Mary Neat, I don't know anything about them. You know something of the ways of Wizards, so perhaps you could inquire about them with the Wizards from that place you stayed."
[color=green]"Congratulations. I'm sure she's a wonderful girl."
[color=green]"When I return home in a couple of months, I'll see what I can find out," Wilhelm says. Mary Neat...Mary Neat...why does that sound familiar? he thinks before he finally makes the connection (just before he falls asleep that night) with Merinita.
[color=green]"The one who calls herself Mary Neat...could it be Merinita?" he asks over breakfast the next morning. [color=green]"Does she have another name? Something Merinita? Which of my sisters is a maga?
[color=green]"Why were they driven out of Rötenbach? And why weren't the rest of you driven out also?"
"They were driven out because of how they behaved. Shameful behavior that brought disrepute on our family." Efforts to get him to clarify it are met with a resistance, and an, 'I'm not discussing it any further.' He said earlier that Kirstyn was the one who was a Wizard.
"Maybe, I'm not at all familiar wth the ways of Wizards and Witches and how they call themselves. Yer-bitte and boney-sags-us and tit-alus. It's beyond me, and I'm fine with that."
About his betrothed, "She is, and I hope you can meet her as..." he pauses, "Well, nevermind."
[color=green]"They are an interesting lot, I'll grant that. I think many of them don't have the same...morals, I guess? As you and I do. I've heard tales of some of their rampant promiscuity as to make you blush to your neck."
He will make small talk most of the trip, gradually letting more and more of himself come out. Telling him the story of how he wound up at the covenant in the Rhine Tribunal, and became friends (after a fashion) with Sylviatos, how he wound up at Mons Electi, about Jormungandr's shenanigans during the floods, how his house was destroyed and rebuilt by Viscaria, and so on. But he also expects Hiltprant to share, also. A tit for tat, as it were. Kind of an exchange of stories back and forth.
[color=green]"You want me to dress as a woman?" Wilhelm says with a look of shock on his face. [color=green]"Hiltprant, I have never worn a gown in my life. I would feel so awkward and out of place, and I wouldn't be myself if I did wear a woman's clothing. Do you want me to meet your beloved as myself, or as someone pretending to be who my family wants me to be?"
He already gave the tit-for tat. Travel to Rötenbach goes fine, it's a big enough party that they aren't bothered by bandits. ((Side note, I may have been in this tiny village, or through it. I know I was at the nearby Titisee. Which as a 17 y.o. boy was hard to not giggle when seeing it. We went paddle boat riding on the lake which is pretty deep, very cold, and the water appears black but it quite clear. I dropped a pfenning in the lake and watched it sink down into its inky depths...))
When they get to Rötenbach, Wilhelm hangs back just a little bit, looking around at everything to see what he remembers, what he doesn't, what he thinks might have changed, and to see all the people. Being a village in the Black Forest, he should still have his Ways of the Forest and Anchored to the Forest intact.
He goes with Hiltprant to wherever (he thinks he remembers which cottage he grew up in, but he doesn't know if he remembers correctly, or if they might have moved) and just kind of stands there feeling awkward.
Rötenbach is the same sleepy little village that Willhelma left all those years ago... But it's strangely quiet. Awareness roll...
"Kommst du, Willhelma." Hiltprant pulls Willhelm's arm to take him into his childhood home...
Per 2 + Awareness 3 + Keen Vision/Sharp Ears (if appropriate) 3 + die roll of 6 = 14 (or 11, if Keen Vision/Sharp Ears don't apply).
Wilhelm goes along.
The village is eerily quiet.... No people, sounds of children. The only people are out and about are Karl-Martin, Hiltprant and the men that accompanied Wilhelm...
Wilhelm looks around suspiciously and comes to a stop. [color=green]"Hiltprant? Where is everybody?" His hands itch for his weapons.