Think of #sen as a filter on the wider porn caption caption archive: same submission pool, but slimmed down to the exact register you searched for.
The internal-link graph around #sen is dense on purpose: related tags at the top, most-viewed further down, and every card links out to its own individual post page with its own share preview.
The tag's structured data (Schema.org CollectionPage + BreadcrumbList) is emitted on every render, so Google and Bing treat this as a real porn caption sub-hub rather than a query results dump.
Every visit reshuffles the sort weights slightly, so the same #sen archive rewards repeat trips — the top of the grid tomorrow won't be identical to today.