Yazdegerd was still observing Usama very cautiously and Usama seemed to do the same. But he didn't look on Yazdegerd with such a caution, but more with interest and perhaps joy, not minding the fact that he was still tied up and basically treated as a hostage. Yazdegerd was the first to start the conversation.
"Do you even understand me?" he asked, nervously looking from Rostam to Usama, back and forth. Usama just smiled with pride in his eyes.
"My Shahanshah, may he be immortal, as a son of son of Imam… eh, prophet is the word? Muhammad, sallallahu 'alayhi wa sallam, I have received an education worthy of my upbringing. With that came, naturally, lessons in Middle Persian."
Yazdegerd was stunned. What this man just said proved a lot of things to him. Firstly, by calling him with the proper title and proper courtesy (My Shahanshah, may he be immortal.), he basically already said that he considers Yazdegerd to be his liege, which was fairly unexpected, considering such a gesture would need proper understanding of Persian customs and social norms. Yazdegerd was also surprised and, in a way, perplexed on Usama's knowledge on Middle Persian. Middle Persian was fairly difficult language for outsider to grasp. And to talk with such a fluency was very admirable. But there was one thing Yazdegerd didn't understand.
"Forgive me for my ignorance, my dear guest, but could you enlighten me in what I presume is basic Arabian courtesy? I am aware of your prophet and also of the high regard he is held in in your homeland. But why mixing Arabic into what was fully fluent Middle Persian monologue?"
Usama immediately understood what Yazdegerd meant, and, well, he partially expected it. Rostam and Jalinus also seemed to not know for sure.
"My Shahanshah, may he be immortal, the line I used is similar to, and forgive my insolence, how I say "may he be immortal" after mentioning you. It's meaning is something like 'Peace be upon him.', but you need not worry about it. You aren't of our religion, and, speaking frankly, it would be more offensive to us if you were saying it than if not."
Yazdegerd was satisfied with the explanation, so he changed the topic once again.
"Rostam, can you repeat what did this man want to offer us? Why did he came here?"
"Of course, my Shahanshah, may he be immortal. He apparently wants a alliance of sorts, offering us classified information in exchange for letting him fight alongside us."
Jalinus was nodding the whole time, as if saying "That's true." the whole time.
"Thank you, Rostam, my spahbed. Is this right, my dear guest?"
"Basically, yes, my Shahanshah, may he be immortal. Also, you can call me Usama, just to make things easier."
"My advisors only told me the basics, so could you elaborate and uncover the specifics? What exactly do you expect from us, and what exactly do you offer?"
Rostam and Jalinus nodded respectively, agreeing with their Shahanshah, not speaking unless allowed. Usama, on the other hand, looked like he was lost in thoughts. Perhaps he was thinking about how he should approach this issue, the way he should explain and present his offer and what words should he use. After a while, no more than twenty seconds, he started talking.
"My Shahanshah, may he be immortal, as common courtesy, I'll start with what I expect from you, so you know in advance. I wish to have your aid in overthrowing current Arab leaders. They not only bring bloodshed, but also suffering and pain not only to lands they conquer and convert by force, but also to their own lands. I can assure you that most people back home want only to live a normal life, worshipping Allah and tending to their livelihood. They don't want war, nor do they want their sons, brothers and husbands to go and die 'in the name of God.'"
"Weren't the Muslim armies composed mainly of volunteers? At least that's what our reports said. Was it all lie?"
"My Shahanshah, the days Muslim soldiers marched into battle as volunteers are long gone. We are a small nation, and most of those few tens of thousands volunteers are long dead. We've since understood that, no matter how strong one may believe, unless he and his home is endangered, not many will choose to voluntarily go to war."
"I see. So those really were volunteers fighting us. Rostam, do you think our zealots would take up arms and fight, in the name of Ahura Mazda?"
"My Shahanshah, as sayidi ibn Zayd said here, given enough threat and danger, I'd say they would. But that is if they really knew of the threat and feel in danger from it."
Rostam answered without hesitation, but still wasn't sure what to think of this question. Yazdegerd, on the other hand, looked as if Rostam's answer satisfied him.
"Continue, Usama. You told us what you seek from us, so now, tell me, what do you offer us?"
"Of course, my Shahanshah, but I want to say one last thing. Were this offer of mine be accepted, I demand you to treat my brethren as you treat your brethren. This is something I can't back on."
Rostam looked very angry and as if he wanted to say something, but Yazdegerd stopped him.
"Usama, who do you take me for. Did you see our cities? Our towns and my Empire? I am the Emperor of Iran and Aniran, my cities in the north house thousands of Christian Armenians and Georgians, while in the south, thousands of Arab and Bedouin traders are travelling between the cities, most of them being Muslim. And, of course, in the east, Hinduism has it's strong community there, in Baluchistan and Khorasan. Jalinus here is also Christian Armenian. Does this prove anything to you?"
Usama smiled kindly. "It does, my Shahanshah. Well then, I shall continue. I know as a fact that you will be soon, in about four weeks time facing the biggest army Arabs gathered yet. And I know the location of the attack. I can offer you this information were you to accept my offer."
Not only Yazdegerd, but also Rostam and Jalinus started paying more attention. Their eyes were widened from shock. The biggest army they gathered yet? How many are we talking about here? And they want to attack in less than two months? These thoughts swirled through their heads. They understood the situation was dire, were Usama speaking the truth, of course. But they couldn't trust him so blindly.
"Usama, I am sure you know how much we need that information, but you also must be aware of the fact, that, to us, you still belong to the enemy, so we can't trust you so blindly. So perhaps we can come to a compromise?"
"My Shahanshah, what I really appreciate from you is the honesty. Forgive me from being rude, but I just don't know whether your honesty comes from inexperience, or from your diplomatic wit. And because I appreciate your honesty, I can offer a compromise. I will tell you all I know, on the condition that you'll accept what I demand from you, and that you'll ensure my safety. I'll stay here, guarded by as many guards you want, until you confirm I was telling the truth by defeating the enemy."
Yazdegerd nodded on both Jalinus and Rostam, allowing them to speak by this gesture.
"I think this is the lowest risk highest reward situation, my Shahanshah. I think you'll be wise to accept this." said Rostam, while his distrust towards Usama seeped from him. "Allow me to take care of his house arrest."
"You have my blessing, my spahbed." said Yazdegerd. Rostam then nodded and walked outside, presumably to gather his most trusted guards.
"My Shahanshah, I also think agreeing with such a proposal is worthy of accepting, but don't you think allowing Rostam to guard our valuable guest is a bit irresponsible?" said Jalinus, whispering to Yazdegerd's ear.
"Don't worry, my hazarbed. I know Rostam will take this responsibly and with honour. But tell him I want half of the guards be made from darigan."
"As you wish, my Shahanshah." answered Jalinus and walked away, chasing after Rostam.
"Now, my dear guest, I am glad we came to an agreement. But I'm hungry. And thirsty. Would you mind some refreshments? After we eat, and after my advisors return, we can continue by you telling us the promised information."
"I share the happiness with you, my Shahanshah. Thank you for your offer of refreshments, I gladly accept it, I myself am quite hungry. But do you think you could untie me? It's starting to get a bit uncomfortable."
"Of course. Guards!" shouted Yazdegerd. From the hallway, just outside of the room they were in emerged two guards, pushtigban, that were guarding the door to the room until now.
"My Shahanshah, may he be immortal."
"Untie this man and stay here, at least until my spahbed and hazarbed return. Also, call me a servant. We are quite hungry."
"As you wish, my Shahanshah."