New update on this! Not updating this one too frequently because I'd like to complete it around the time they actually get engaged and we don't have a time frame for that yet. Got the basic idea while chatting on Fanforum.
Penny answered the door within seconds of hearing the knock. "Hey Raj. Come on in."
"Thank you," he said. "So, what sort of helpful advice may I provide you this time?"
"C'mere," Penny said, settling down the couch.
He sat next to her. "What's up?"
Penny smiled. "I'm going to ask Leonard to marry me."
Raj's jaw dropped and the corners of his mouth turned up. "Oh my gosh!" He exclaimed. "That's incredible! I'm so happy for you guys!" He leaned over to give Penny an enthusiastic hug.
"Aw, thanks Raj," she said.
"When are you going to do it?" Raj asked, keeping a hand on her arm.
"Soon," she said. "I haven't figured out exactly how, though. I was hoping you could give me some advice?"
"Sure!" Raj said. "I'd love to! Okay, first off, you'll want to completely sweep him off his feet. Maybe if the two of you are at a screening of…"
"He said nothing on a big screen."
"You're going to ask him to marry you and he has ground rules?" Raj asked.
"Well I don't want to make him uncomfortable!" Penny said.
"He's getting to have sex with you the rest of his life, I'm sure he'll get over it." Penny frowned. "I'm sorry," Raj said, "that was crude, okay no big screen. You could get a bunch of people together in a big song and dance number that would end with you-"
"Please tell me you're not describing something that happened on Glee."
"…that would end with you saying 'oh, just kidding, this isn't anything like Glee'," Raj finished. "Ooh, what if you sent him on a long elaborate scavenger hunt and the final clue is where you are?"
"I don't know," Penny said. "I feel like that's a little cliché."
"Do you want my help or not?" Raj asked.
"Yes!" Penny said, scooting closer to him and putting her hand on his shoulder. "Yes, yes, yes! This needs to be perfect."
"You know, Penny," Raj said, "all jokes aside…Leonard loves you. It doesn't matter how you do it. You…on your knee…looking up at him…and asking him if he would do you the honor of becoming your husband, that's like his favorite dream come true."
"Really?" Penny said.
"Penny, do you remember when you asked me for advice on how to make a romantic gesture?" Raj asked.
"Well, yeah," Penny said.
"And what ended up completely melting his heart had nothing to do with my advice. It was because of you. So this time, my advice is to just be your open, honest self. Because that's the woman that he wants to spend the rest of his life with."
Penny smiled at that. "Okay. I'll think of something."
Both Penny and Raj jumped when her apartment door opened and Leonard walked in. "Hey, I'm…" he looked confused for a moment. "Hello, Raj."
"Hey Leonard," Raj said.
"What are you doing here?" Leonard asked, putting his bag down near the door. "Sheldon drive both of you out of our place?"
"Penny needed to ask my advice on something," Raj said, glancing toward her.
"Oh." Leonard seemed to consider the answer acceptable.
"I helped her as much as I could," Raj continued, raising his eyebrows at Penny. She gave him a quick smile, and bit her lower lip, glancing over at Leonard. "But there's a fundamental question that I think she really needs you for."
"Sure," Leonard said, walking over and leaning down to give Penny a kiss. "What's up?"
Grabbing his hand, Penny got up and pushed him toward the kitchen to give herself more room. "What I was wondering," she said, smiling at him. "Was if you, would, well…" she slowly lowered herself onto her knee, still holding his hand. "Want to marry me."
Leonard was grinning broadly before anyone had the time to blink. "Of course I'll marry you," he said, pulling her up and throwing his arms around her. "Of course, Penny."
"Yippee!" Raj said, jumping up and rushing, arms out, to join in on the hug.