List members will be a new form of public representative in Ontario. Their roles will be virtually identical to the roles of riding MPPs with one major difference: riding members take constituency work from one riding, list members take constituency work from anywhere in the province. They make it possible for our legislature to reflect how the greater populace actually voted.
List members will be required to respond to concerns raised from any Ontarian, not just those in one constituency. List members won't be bound by the usual urban/rural, geographical/regional divides. As a result, list members will be able to devote more time to specific issues of provincial concern and work more often on legislative committees. This will actually free up local members to focus more on local issues.
Under a system like Mixed Member Proportional, most candidates who run on party lists also run as candidates in individual constituencies. The rationale is that most governments under MMP receive few if any list members (because winning parties normally don't need a top-up of list members to ensure their representation matches their popular vote). Alternatively, parties that lose elections elect a smaller number of constituency members, and therefore need a top-up of list members. Thus, it's likely most list members will have run but lost in a district seat in the last election. Those elected from the list will benefit from having sought election and faced voters directly in a district seat. If they want to participate in the next government, they'll likely have to run for a district seat again. This will likely not be a rule under the new system, but it'll likely be the practise.