A/N: This idea was living rent free in my mind for years. The concept behind this is that Tarn's vocal powers carries over through recordings; however, since Megatron wanted to kill Optimus on his own terms, Tarn wasn't allowed to kill him via voice recording and deliver it on a silver platter.
It's not the most logical explanation nor canon but shut up lmme indulge my fantasy since no one else wrote it.
.o
Soundwave was essentially an archive of the world around him. He had petabytes worth of audio and video recordings saved in his processor. There were too many potential instances where a long-lost soundgrab could tilt the war in the Decepticons' favour.
As he had many, he had organized the recordings into different folders. Many found themselves in the miscellaneous bin; Megatron had his own separate folder; rumours and possible dissent; flattery, mechs sucking up to him. Then there was the folder of things that were pleasing to his optics or audials.
He wasn't a fan of music, but he was appreciative of voices. Especially musically-inclined robots. One notable one was a now-Autobot designated Jazz. The mech's harmonic voice was pleasant, with the cycling ups and downs of his vocal output that was extraordinary and rare, and even the recordings where the mech was singing was stored on his processor. He may not have liked singing, but there were some mechs that made it tolerable. The mech had little history, but through the act of raiding other mechs' processors, a few video recordings were gathered of Jazz's pre-war life, which involved dancing in addition to singing. He would have looked quite lovely writhing in pain, Soundwave surmised.
Of particular interest was a Decepticon known as Tarn. His talents had a special place in Soundwave's processor. The Decepticon was leader of the 'Decepticon Justice Division', something Soundwave did not care for nor pay much attention to unless directed to by Megatron himself. The DJD didn't seem to make itself a contender to the forefront of the war, instead dealing with traitors and unrest. Unfortunately, Megatron had excluded Starscream from their touch.
Tarn seemed to be a fanatic of the Decepticon cause to an unhealthy extent. Soundwave had mused at one point that perhaps the mech fantasized about being in Soundwave's position, one surely coveted by a mech like Tarn, as it was a position third closest to the Decepticon leader himself. However, upon passing by the mech at one point with a brief glimpse through his processor, Soundwave was surprised to find the exact opposite. The mech seemed to have an affinity for him as well. Soundwave attributed it to his position and marked it away in his profile of Tarn. Just another screwloose.
When he witnessed Tarn's ability in action, his impressions of Tarn changed. The mech's Voice could kill a mech.
Soundwave didn't consider himself a masochist, but after experiencing the effects of Tarn's Voice, he might have discovered a side of him he didn't think he had. Recordings of the tank's ability were few and far between, mostly because anyone who was in range of it was in danger of their spark being extinguished. And who would want to stick around to watch an execution as brutal as the ones the DJD utilized?
Those were one of his treasured collections. Tarn's Voice did hurt, even through recordings, which Soundwave found fascinating. Transmission of feelings, whether pain or pleasure, were only ever documented in direct memory sharing such as through a sparkmerge or plug-in-port interfacing, or in his case, mental assault. Perhaps that was one of the reasons why recordings of Tarn fancied him so.
Despite the rumours about him, he was a mech with a healthy libido. He didn't have time to pursue it, and when he did, the people about him were unsavory in taste, causing him to make company with his own hand. In the rare instances where he had time to himself, his go-to pleasure bank was in the memories of the processors he'd interrogated and ripped through, feeding off the sensations from those memories. He didn't truly know the mechs that were interfacing in the memories, yet because memories transferred feelings in telepathy, he felt it all.
With Tarn, it was a different level of feeling. One that he ached for. He sat there in his rare time off, playing back one of the more recent recordings he'd obtained of Tarn. The DJD had been executing a MTO who was attempting to default to Neutral status in order to appease an Autobot femme he'd fallen for. The femme was the bot Soundwave had passed several orns ago—sheer coincidence, but what a lucky find it was in her databanks. The femme had witnessed the entire event from a distance in hiding. Her lover, extinguished before her very eyes.
Soundwave gripped the armrests of his chair. Tarn was speaking lowly—very hard to hear, especially over the femme's increasingly panicked ventilations. He could feel the Voice being fed into their audials, noticeable pain evident on the defector's face. Each word was a lance to Soundwave's spark, causing it to clench panicked in his chamber. It was registering pain. One could attribute this to memories transmitting pain, but audio-only recordings of Tarn produced the same results.
When Tarn crooned in that svelte voice, Soundwave let out a shaky his, plating loosening despite the natural instinct to clamp up in reaction to pain.
Soundwave contemplated what he would want Tarn to say before his execution—not that he ever planned on abandoning the Decepticon cause, no. The thing about fantasies is that they don't often have to make sense. Soundwave could conjure a fanciful notion of his death without letting the concept of treason or eternal termination kill his charge.
One hand was able to unclench from the chair to flit against his chest. His spark chamber wasn't visible despite the transparent glass of his cassette deck, but the touches would suffice. The odd combination of slight strokes of pleasure mixed in with the brute stabbing of his spark allowed his charge to increase in a way that browsing through people's mindporn didn't accomplish. His chest felt like it was crushing in on itself, his life force growing weaker with suffocation…
Before Tarn could do the deed and finish the bot off, Soundwave had to turn it off. He gasped, collapsing in his chair as though an entire day of hard work had gone by.
He was never able to listen to the entirety of a recording of Tarn's work all in one sitting. Too much exposure might mean certain death, even if Tarn's voice wasn't specifically tuned to Soundwave's spark frequency. Soundwave didn't know the consequences, and he was wary to risk testing it on himself to watch a video all the way through in one go.
He hated that he had to service himself off to completion rather than finishing with the end of the video. He snarled as he shoved his fingers into seams of his hips, mercilessly and roughly tugging at wires in his joints, causing feedback to increase, rolling them between his fingers until it was just enough to tip him over the edge into an overload. He could have finished with his spike, but with Tarn's videos, he'd never had to resort to that because of how close they left him. Playing with his circuitry and cording was the most easy access route to completion.
He sighed as he came down from it, twitching in his fingers. He wanted to hear that voice in person. Wanted to know if it was as horrible as memories and recordings depicted it. Wanted a recording straight from his own optics, his own experience.
Perhaps he should pay a personal visit to the Decepticon Justice Division.