Passive in this sentence question

I'm not sure about the usage of the passive in this sentence - Context: Some people went into an another world and came back - (context sentences: 魔法が使えないはずの人がなぜか突然移動してしまったことがあり、運よく戻ってきた人の話が伝えられている。共通しているのは、皆一様に「奇妙な」ものを見てきたということだ。)
そして、必ず「変わった服を着ている」と言われること。

I think there are 2 possibilities:
1. Assuming that 戻ってきた人 are also saying 「変わった服を着ている」=honorific passive usage.
2. On the other hand, maybe 奇妙なもの (or someone unspecified) are saying 「変わった服を着ている」on 戻ってきた人(=受身), i.e., indirect passive. My random guess would be that it's the latter, just because of ということだ. Think it would probably be after the last sentence to include it under the " things in common that 戻ってきた人 said". *shrugs*
Can any one tell me if those 2 are possible in this context and/or which one it is?

Side question, just to be sure, the 見てきた here is "saw (something) and came back", right?

The people who returned had "変わった服を着ている" said to/about them (not by the 「奇妙な」もの, just by people in general). So the two things all these cases have in common are them seeing strange things (reported by the people who return) and them wearing strange clothes (said presumably by people who see them when they've just returned).

Right on 見てきた.

Thanks for the help. So let me get this straight,

「奇妙なもの」= said by 戻ってきた人 (describing the things they saw while in the other world)
「変わった服を着ている」と言われる (said after they returned from the other world) = Some (unspecified) people=主体 ; 戻ってきた人=受身, correct?

「奇妙な」ものを見てきた/見た: describing about the things 戻ってきた人 experienced while in the other world
(「奇妙な」ものを見てきた is not (always) what 戻ってきた人 really said, since いう doesn't mean "to say" here.)


「変わった服を着ている」と言われる
「変わった服を着ている」: what people who saw 戻ってきた人 said
戻ってきた人 is the subject(主体) of the passive(受身) form 言われる （戻ってきた人が/は「変わった服を着ている」と言われる）

Probably you understand the functions of 戻ってきた人 and "people who saw them" correctly, but the use of the terms 主体 and 受身 seems not accurate. Sorry for nitpicking.

I see. It's fine, I like nitpicking . I always assumed that 受身 would mark the receiver of the passive action :/.
Would you mark the agent in the passive sentences with 動作主? Also, what would 主語 (subject/topic of the sentence, not action doer) mark? I'm still trying to learn these terms. I thought that 主体 (doer of some action) would mark the agent, while it marks the receiver of the passive action, as you wrote. I guess it was strange to me that 戻ってきた人= 主体 in the passive sentence since someone else is doing the action.

主体= 「自覚や意志に基づいて行動したり作用を他に及ぼしたりするもの。」
主語= 「文の成分の一。文の中で，「何がどうする」「何がどんなだ」「何が何だ」における「何が」を示す文節をいう。「犬が走る」「空が青い」「花散る」における「犬が」「空が」「花」の類。主辞。」; 「文の成分の一。文において、述語の示す動作・作用・属性などの主体を表す部分。」
There's also 主題, no idea what that would mark.

Since 主体 apparently marks a subject who has volition, how would the these be marked with 主語? - 記号や色 and 交通信号 from 記号や色がある意味を示す and 交通信号の赤は『止まれ』を―・す, respectively.

Side question: how it 他に (to other(s)) read in this case? たに?

I also apologize for nitpicking.

Ah, then you probably mixed up 受け手(receiver) with 受身. 受身 only means "passive". ;-)

動作の主体 / 動作主体 / 動作主 means agent, as you wrote, but 主体 usually refers to 主語. Actually, just 主体 is a bit ambiguous. In fact, there is a term 被動作主体 "the object / target / receiver of the action". (This is also an answer to one of your questions. 動作の対象 or 被動作主 is used, too.)

主語 is the subject and 主題 is the topic. 主体 has nothing to do with "volition". For instance, in a sentence 木の葉が落ちた, 木の葉 is 主語, and also 現象の主体. Similarly, 本 is 主語 and 存在の主体 in 机の上に本がある.

As for the reading, yes, that's たに in that case.

I see, thanks for explaining it. 1 last question. Can I bother you a bit more to explain how 主体 is ambiguous? It's a bit confusing since 大辞林 and 大辞泉 keep insisting that 主体 by itself "has" 自覚や意志. I did some random searching and 主体 by itself seems to mostly refer to human subjects, e.g., 交通信号 must be a 主語, while I think if there was a person showing something, it is would be just 主体. But then again, 大辞泉 has 主語 described as 「述語の示す動作・作用・属性などの主体を表す部分 Unless 主体 has a different meaning here and it's not limited to 自覚や意志?

In the sentence 戻ってきた人が(彼らを見た人に）「変わった服を着ている」と言われる, 戻ってきた人 is 被動作主体 and 彼らを見た人 is 動作主体. Thus, (even though one of them is omitted) there actually are two 主体s in a single sentence, and just 主体 is unclear which one it is referring to. That's why I said "ambiguous".

Your quotation from the dictionary is the definition of 主体 in philosophy. It's different from the definition of 主体 as a term used in grammar or in general use. You can see the second definition "２ 物事を構成するうえで中心となっているもの。" doesn't mention "intention" at all. Subject and object in philosophy have completely different definitions from the ones in grammar also in English. You mixed them up also here.

Unlike in philosophy, inanimated things such like 交通信号 can be 主体 in grammar. The words indicated by が are all 主語 in the examples below, of course.
e.g.
交通信号が倒れている（現象の主体）
薬が効いてきた（作用の主体）
空が青い（属性の主体）

Ahhhh. No wonder this didn't add up. Thanks for clearing it up, I appreciate it. Guess I should be more careful with dictionary entries in the future :/.