Ron and Hermione had hit a wall when it came to destroying Voldemort's remaining Horcruxes. Everything that could work was either unavailable or out of their reach, and they had no time to learn Fiendfyre well enough to cast and control it properly.
Not that Ron had much faith in his intelligence - if even Hermione could not figure it out so far, what chance did he have? Still, he had to try for the sake of everyone he cared for. The redhead thought of his sister and how she was tricked into serving Voldemort in her first year. He couldn't fail Hermione, and he couldn't fail Ginny either.
Her sister was lured into... that was it. They had what they needed all along and more.
"Basilisk fangs!" he cried out triumphantly. "I'll go to the Chamber of Secrets and pick some!"
"Brilliant idea, Ron! Why didn't I think of that?" Hermione cheered, impressed.
"Hey, you're allowed to have an off day after doing enough thinking for the three of us all the time." Ron laughed good-naturedly.
"But are you sure you can open the entrance? You're not a Parselmouth, and not even Dumbledore could emulate Parseltongue even though he can understand it." Hermione second-guessed worriedly.
Ron stayed silent for a few moments to consider. She had made a good point, but he wasn't going to be defeated by a mere technicality.
"Just you wait. I'll come back here loaded with fangs." he protested. "I have my ways." He went off to finish the job.
He strode towards the entrance. While the redhead knew it could only be opened with Parseltongue, he didn't have to be the one speaking it.
"Serpensortia!" he said. A large snake emerged, hissing threateningly.
"Imperio!" he cried out. "Now say open in Parseltongue." he mentally commanded.
The snake opened the entrance, and Ron vanished it. He collected all the basilisk fangs he could, then went back.