What ties the list together?

Common thread

1. Proper nouns that contain ordinary English words – each entry pairs a familiar first name with a word that exists independently in the language (rose, pepper, doe, joe, mason, etc.).
2. Generic/placeholder usage – several of them (John Doe, Joe, Maria, Bobby) are traditionally used as stand‑in names when a specific identity isn’t needed.
3. Presence in standard word‑list datasets – all of the names appear in the verified word lists used for computational linguistics and programming exercises (e.g., lowerwords.txt includes “bobby” ⁴; words.txt contains “joe,” “rose,” “pepper,” “doe,” etc. ⁶⁷⁹).

Thus, the shared characteristic is that these are well‑known proper nouns that also function as everyday English words or generic placeholders, a fact reflected by their inclusion in the cited word‑list sources.

Supporting evidence from the sources

• The Duke lowerwords.txt file lists Bobby among common lower‑case words ⁴.
• The Topcoder words.txt and Penn words.txt collections contain entries such as rose, pepper, doe, joe, and mason, confirming that the non‑name parts of each phrase are recognized English words ⁶⁷⁹.
• The placeholder nature of John Doe is a widely documented convention for anonymous individuals (common knowledge, reinforced by multiple AI analyses).

Why other interpretations fall short

• Soap‑opera or band‑only explanations (as suggested by one model) do not account for the majority of the items, many of which are not tied to any specific drama series.
• The notion that the list is merely “a collection of proper nouns” is true but too broad; the more specific link—everyday words/placeholder usage—captures the nuanced pattern observed across the items.

Bottom line

All nine entries are recognizable proper nouns that embed ordinary English words and serve, in many cases, as generic or placeholder names, a pattern that is reflected in their presence within standard lexical resources.