Seamus swallowed slowly, part of him not believing that he'd just agreed to do this. There were very few people - practically none outside of his family - who knew that he had a bit of a talent for singing. Lav knew, because she'd known him so long, and Dean, though he'd never sang in front of his best mate. It wasn't exactly the sort of thing that went on in the boys' dorms.
He took a deep breath and looked into her dark eyes, which were shining at him in anticipation. Very softly, he began singing happy birthday to her, but he chose to sing it in Gaelic, he felt a bit less embarrassed that way.
"Lá Breithe Sona dhuit, Lá Breithe Sona dhuit, Lá Breithe Sona a Parvati, Lá Breithe Sona dhuit." He smiled at her before nodding in the direction of the cupcake. "Better make your wish before the candle's gone," he murmured. He ducked his head, feeling himself blush a bit and hoping she couldn't see.